I did a terrible thing today.

You remember Ruth Wallace, my neighbour in the wheelchair? You know how nasty she is to me, and how I try to ignore her when she says or does all those mean things?

Well, today I failed. Today I finally lost my temper with her, and I think I may be in very big trouble now, even bigger than the shoplifting.

Here’s what happened. When I got up this morning, I discovered we were out of milk, so I shouted up to Dad that I was going to the shop, which is just two blocks away. As soon as I came out I saw her, just sitting by her gate, all muffled up because it was pretty cold, with a furry black hat on her head and a brown and orange check blanket over her legs.

When she saw me coming she actually smiled, and I automatically smiled back – well, half-smiled. I didn’t feel like giving her a proper smile.

As I walked past, she stuck out her hand and grabbed my wrist, and boy, were her fingers freezing – like ice. I opened my mouth to tell her to let me go, but before I had a chance, she said, kind of softly, ‘I’m just wondering what it feels like.’

I thought she meant my hand. I tried to pull away, but she held on tight. And do you know what she said then?

She said, ‘What does it feel like when your mother leaves you?’

And the awful thing is that she was smiling all the time, this horrible fake smile, and she had a bit of a Cornflake or something caught between her teeth, and I pulled my arm away and walked as quickly as I could down the road, and I could hear her laughing, and then these tears just came out of nowhere, and I had to keep wiping them away, because I couldn’t see where I was going.

And all the way to the shop, I could feel the tingle that I always feel when my temper is just about ready to be lost. I kept hearing her laughing, sitting there in her horrible wheelchair and laughing at me. I bought the milk, in one of those plastic litre containers with a handle, and a pack of tissues so I could dry my face up. No way was I going to let her see that she’d made me cry.

She was still there when I got back, still sitting there, grinning away. I walked towards her, trying to ignore her, trying to keep my temper under control. And if she’d said nothing, I don’t think I would have done anything, I really don’t – except maybe given her a filthy look.

If only she’d kept quiet.

But she didn’t. She watched me as I walked towards her, and then she said, in this horrible pretending-to-care voice, ‘Hey Liz, have you been crying?’

And that did it. Something came racing up inside me like a tidal wave. I lifted the plastic container of milk and I rammed it down onto her legs as hard as I could, and then I turned and ran. I bolted in our gate and up the path and around to the back of the house, right down to the bottom of the garden.

My heart was thumping really loudly, and my hands were shaking – I had to wrap them right around the milk to keep from dropping it. It was a cold morning, I could see my breath coming out in fast little puffs, but I didn’t dare go into the house. I was afraid Ruth Wallace’s parents would come banging at the door, looking for me.

After a while I had to move, I was so cold. I walked up the garden on legs I could hardly feel and opened the back door, sure that Mrs Wallace would be inside, waiting for me. But there was nobody there except Dad, wondering why I’d taken so long. No sign of the Wallaces at all.

All through breakfast, which I had to force myself to eat, I kept waiting to hear the doorbell. When it finally rang, I almost fell out of my chair, but it was just the boy who delivered our paper, looking for his money. While Dad was talking to him, I crept into the sitting room and peeped through the window.

Nobody in next door’s garden, no sign of anyone. No shouts of anger coming from the house. Nobody storming out and turning in our gate with a face like thunder. I couldn’t understand it.

And now it’s almost bedtime, and I haven’t dared to put my nose outside the door all day. Chloe came around after lunch and we watched a film with Colin Farrell in it, and I haven’t a clue what it was about, because all I could see was my arm lifting up the milk and bringing it down with a thump on Ruth Wallace’s useless legs.

I wish I could start today all over again. I wish I could rub it out and begin again.

I wish Mam was here now. I know I was mad at her for not coming home, but it’s only because I miss her so much. Sometimes it feels like a real pain, right in the middle of me, where I think my heart must be. Other times it’s like I’m empty, as if someone came along and held me upside down for a while and let everything fall out.

That’s how it feels when your mother leaves, Ruth Wallace.

I wish this was all a crazy kind of dream, and I could wake up and Mam would be there with my breakfast on a tray, like she used to do some weekend mornings, with a soft boiled egg and brown toast soldiers, or a bowl of lump-free porridge topped with a blob of blackcurrant jam. I wish I had magical powers like Harry Potter, and I could wave my wand and change everything back to how it used to be.

I wrote this text to Mam a while ago:

Hit Ruth Wallace on legs with milk. Please help.

– but then I got scared, and deleted it. I can’t tell Mam what I did. I can’t tell anyone.

I hope to God Ruth Wallace is OK.