The next morning I was feeling very nervous about going back to school. I just knew everyone would be talking about the party. It was major gossip material, made worse by the fact that Leo was the one who had caught us. I couldn’t help thinking how lucky it was that it had only been Leo (without Mum) who had caught us at Blossom House on Saturday night. If Mum had been with him, there’d have been no way to prevent their big secret coming out. At least now we could pretend it was pure coincidence that Leo happened to be passing. And since no one at school (apart from Lily) knew the truth about them, there was no reason for anyone to suspect anything different.

Leo left for school before us with strict instructions to both of us not to be late. Why, oh, why did we have to have Leo as our registration teacher this week of all weeks?

As we ate breakfast, Sean suddenly clutched his stomach and complained that he felt sick. If you ask me, he was just feeling nervous too, though Mum immediately started flapping and telling him to get up to the bathroom because she didn’t want him throwing up all over the table. (He did that once when he was younger and Mum’s never forgotten it.)

Since she didn’t go upstairs with him, Mum couldn’t really argue when he came down five minutes later and reported that he’d been sick in the loo. She told him to go to his room to rest and ignored my disbelieving face as she phoned the school to say he wouldn’t be in.

And not for the first time I wished Mum wouldn’t be quite so amenable every time Sean decided that he needed the day off.

The trouble started as I crossed the playground just after the bell had rung. Becky Addams, a Year Ten girl I hardly knew, came and stood in front of me. Her mates were quick to follow.

‘Hey, Sasha! Is it true your mum’s shacking up with Mr Anderson?’ she asked.

‘What?’ My voice came out so hoarse that even I could hardly hear it.

‘Come on, Sasha! You can stop pretending. Everybody knows!’

I was starting to feel really light-headed as they fired questions at me:

‘So how long have they been together?’

‘Come on, Sasha! We want to hear all the juicy bits!’

‘Yeah, Sasha! Dish!’

‘So have you seen him in his pyjamas?’

‘Does he snore?’

‘Does he actually wear pyjamas?’

‘How do you ever get to sleep at night knowing he’s in the same house as you?’

‘Does he work out?’

‘My mum says he’s got to be about half your mum’s age! Is that true?’

‘Yes, Sasha … is it even legal for them to be together?’

They all laughed and I tried not to let them see how humiliated I was. How did they know?

Just breathe: in and out … in and out … in and out …

I stood still as their voices swirled around me as a single mass of noise, muffled only by the loud thumping sound in my head as the blood pumped round it furiously.

I just couldn’t get over the fact that they all knew. Because I was absolutely certain that nobody had known on Saturday night. I thought really hard. I knew I’d called Leo by his first name while Sean was trapped in that box, but nobody had commented at the time and I was pretty certain no one had noticed. Had I got that wrong? Or had there been some other clue that he was more than just a teacher to us?

As they all carried on laughing, I walked away, wishing I didn’t feel so helpless and alone. If only Sean was with me … or, better still, Lily.

In fact where was Lily? Normally I’d see her in the playground at around this time. And if she saw me being picked on she’d be the first one to rush over to back me up. Today, however, there was no sign of her, or any of her pals.

My legs felt wooden as I somehow forced them to carry me into the school building towards my registration room. Oh, God, did Leo realise that everyone knew? Would anyone in our registration class say anything? Some other kids were giggling and whispering as they walked past me. Were they talking about Leo and Mum? How was I ever going to get through a whole day of this?

Just then I saw Clara and Hanna. When they spotted me they both started grinning.

‘Hey, Sasha,’ Clara greeted me. ‘Listen, I know Lily says it’s no big deal about your mum and Mr Anderson. But you know what?’ She paused dramatically. ‘It really, really is!’

Hanna started giggling then.

I froze. ‘Lily told you it’s no big deal?’

‘Yeah … well, Lily always has a soft spot for you underdog types!’

‘Get lost, Clara!’ I snapped, while in my head one word was repeating itself over and over: Lily, Lily, Lily …

Lily had been the only one who knew about Leo and Mum!

And tears started to prick my eyes as I realised who must have given away our secret.

It was beginning to feel like the worst day of my life. Well, OK, not really. That was probably still the day my dad died, but at least on that day I’d been too young to fully understand at the time just how bad a day I was actually having. (I mean, I know now just how final a thing dying is, but back then, when the grown-ups told me he was gone, I kept on imagining him as kind of waiting in the wings somewhere rather than gone for good. Though seeing the bereavement counsellor helped me a bit with that, I suppose.)

I ended up avoiding registration and hiding out in the girls’ toilets instead. I know it must sound daft, but I couldn’t imagine feeling more shaky if someone had just told me Lily had been run over by a bus.

Come on, Sasha. Get a grip. Nobody died.

But Lily had still betrayed me, and that felt so huge that even focusing on my breathing didn’t make me feel much steadier.

As soon as the bell rang to signal the end of registration I set off to find Leo in the English department office.

‘Sasha, where have you been?’ he asked in a concerned voice as I met up with him just outside the door. ‘Is something wrong? Where’s Sean?’

‘Sean’s OK,’ I reassured him at once. ‘He’s off sick today.’

‘Really?’ Leo was frowning.

‘It’s nothing serious,’ I added, knowing that my brother avoiding school was the least of our worries right now. ‘Leo, I’m sorry but I couldn’t face coming to registration.’ I lowered my voice to a whisper. ‘People know about you and Mum.’

Leo actually swore – which is something he hardly ever does in front of us, and absolutely never does in school (well, not within earshot of any pupils, in any case).

‘Sorry,’ he apologised, going a bit pink as he added, ‘I guess that explains all the sniggers I was getting in registration this morning.’

I swallowed over my dry throat. ‘It was Lily who told them.’

‘Lily? How did she know?’

‘She’s known for ages, Leo! She’s my best friend. I couldn’t keep it a secret from her.’ I felt on the verge of tears again.

Leo must have clocked my distress because he immediately softened his tone. ‘It’s OK, Sasha. Your mum and I didn’t mean to keep it a secret forever in any case. Perhaps it’s just as well it’s out in the open.’ He put his hand on my shoulder and guided me out into the corridor, where other pupils were hurrying to their first lesson of the day. ‘You’d better get going to your next class. We’ll talk about this tonight. But, Sasha, now that it’s out there, try and pretend like it’s no big deal, OK? The less of a reaction people get from you, the quicker they’ll stop teasing. This will be a five-minute wonder, you’ll see. In a couple of weeks something else will be the new hot topic. We just have to hold our heads up in the playground – and in the staffroom – until then. Deal?’

I sniffed, feeling slightly better that the two of us were in this together. ‘Leo, are you going to get into trouble about this?’

‘Hey, don’t you worry about me. Though I’d better go and speak to Mr Jamieson before he hears about it on the grapevine.’ He pulled a bit of a pained face, which made me smile despite the direness of the situation. Sometimes I forget that our fearsome head teacher is Leo’s boss and that Leo is just as keen to stay on the right side of him as we are.

As I headed for my first class, I groaned. It was PE and Lily, Clara and Hanna were all in the same class as me. Luckily, so was Priti, and I made up my mind to stick with her and try and ignore the others.

I was the last person to arrive in the changing room and only Priti and a couple of other girls were still there getting ready. Everyone else was outside warming up for cross-country running. (Basically that means jogging round the boundary of our school, through the little park next door, then back round the boundary again.)

As I greeted Priti it took me a few moments to realise she wasn’t going to reply. I waited until we were the last two in the changing room before asking her outright what was wrong. She flounced her ponytail aggressively and said that if I didn’t know, then she wasn’t going to tell me.

I couldn’t think what she was so cross about – unless she had heard about Mum and Leo and didn’t approve for some reason. But why wouldn’t she? Sure, there was the age difference, and the fact that Leo was my teacher, but why would she be upset about that? I shook my head, not understanding what the problem was at all.

‘Come on, Sasha! Get a move on!’ Mrs Delaney, our PE teacher, called out from the doorway. I didn’t know if my teacher had heard about Mum and Leo yet, but in any case all the teachers would know soon enough, and then my humiliation would be complete. Maybe I could convince Mum to let me switch schools, I thought miserably. Or maybe I should copy Sean and pretend to be sick.

I was jogging on my own round the first corner – which is where all the slackers stop running and start walking and chatting to their mates – when I heard my name being called.

Lily was standing waiting for me – and not just Lily, but Clara and Hanna too. My heart was pounding away furiously.

‘Sasha …’ Lily began, looking nervous. ‘Listen, I need to tell you something –’

I hadn’t wanted to talk to her at all. If I could have avoided seeing Lily for the next ten years, I would have. But I didn’t for one moment expect her to try to justify herself to me.

‘A secret is a secret,’ I interrupted her. ‘You promised you wouldn’t tell anybody, Lily! You promised! You’re meant to be my best friend!’

‘Sasha, I am your best friend but –’

‘YOU’RE NOT!’ I screamed, all the stress and tension of the last few days bursting out unchecked. ‘FRIENDS DON’T DO WHAT YOU DID!’ Then I ran on away from her, racing along the muddy track round the edge of our school, not stopping until I got a stitch in my side and Lily had been left far behind. Tears were streaming down my face and my nose was running. I wiped the whole lot with the front of my T-shirt. Nobody was watching and, even if they were, I didn’t much care.

I looked up and realised that Priti was just ahead of me, jogging steadily and not looking back. Don’t ask me why, but I think she knew I was there.

I panted as I pushed myself to catch up with her.

‘Priti, wait! Please tell me why you’re so mad at me!’ I gasped as I finally got close enough to talk.

Priti glared at me, looking very hot and very angry. ‘Why didn’t you tell me about your mum and Mr Anderson?’

‘I couldn’t, Priti. Mum made us promise –’

‘You told Lily!’ She had slowed to walking pace now.

‘I know, but only because … because Lily …’ I trailed off, suddenly seeing why she was so mad – and knowing there was nothing I could say at this point that wouldn’t make things even worse.

‘Don’t worry! I get it! Lily’s your best friend, not me! Still …’ She let out an almost triumphant snort. ‘It seems like you were wrong about being able to trust her, doesn’t it?’

‘Priti, I …’

I slowed down and let her go on ahead of me.

She was right of course. I had picked the wrong friend to trust. It had just seemed natural to tell Lily. I mean Lily had been my best friend for so long that I’d always felt like she knew all my secret stuff even before I told her.

Lily had changed, I decided. And it was Clara and the others who had done it. And I had been really blind not to see it.

Tears were welling up in my eyes again as I trudged round the remainder of the course. In just a few hours I had managed to become the most ridiculed person in school and lose both my best friends.

I had never felt so lonely.