Debbie Johnson - The Birthday That Changed Everything - Perfect summer holiday reading!

And at the bottom of the e-mail, rolling across the page in all its before-and-after glory, was an advert. For bloody Botox. I stared at it and gave some serious consideration to smashing the laptop to pieces with a sledgehammer.

Instead, I remained calm and in control of my senses. At least calm enough to not wreck the computer.

The only problem was what to do next. When you get news like that, especially in the deeply personal format of an e-mail, it renders you too stupefied to feel much at all. I think my brain shut down to protect itself from overload, and I did the logical thing – started making lunch. Lucy would be back from a trip to Oxford city centre soon with her friends Lucifer and Beelzebub. Well, that was my name for them. I think it was actually Tasha and Sophie, but they’d changed a lot since Reception, and I wasn’t sure if they were even human any more.

They’d left earlier that morning on some sort of adventure to mark the end of the school term. They were probably sticking it to the Man by shoplifting black nail varnish from Superdrug.

My son, Ollie, was out at Warhammer club at the local library, where he took a frightening amount of pleasure in painting small figures of trolls and demons various shades of silver. He still looked like a normal fourteen-year-old, at least – apart from the iPod devices that had now permanently replaced his ears. I’d got used to raising my voice slightly when talking to him, a bit like you do with an elderly aunt at a family do, and playing ad hoc games of charades to let him know dinner was ready or it was time for school.

They’d both be coming home soon, even if Simon wasn’t, and they’d be hungry, thirsty, possibly lazy, grumpy, and a variety of other dwarfs as well.

On autopilot, I opened the fridge door and pulled out some ham, mayonnaise and half a leftover chocolate log, starting to assemble a sumptuous feast. Well, maybe not that sumptuous, but pretty good for a woman who’d just been cyber-dumped.

Simon was leaving me, I thought as I chopped and spread. Leaving us. My handsome husband: orthopaedic surgeon to the stars. Or at least a few C-listers who’d knackered their knees skiing, and one overweight comedian who snapped his wrist in a celebrity break-dancing contest.

It didn’t seem real. I couldn’t let it be real. Our marriage had survived way too much for it to fall to pieces now. Me getting pregnant when we were both student doctors working twenty-hour days. Lucy arriving, Ollie soon after; struggling to cope on one wage as Simon carried on with his residency. The miscarriage I’d had a few years ago, which devastated us both, even though we hadn’t planned any more…seventeen years of love and passion and anger and boredom and resentment couldn’t end with an e-mail, surely?

Except I knew marriages did end, all the time. At the school where I work as a teaching assistant, the deputy head’s husband had recently run off with a woman he met through an online betting website. Apparently they bonded over a game of Texas Hold ’Em and next thing she knew, he’d buggered off to Barrow-in-Furness to start a new life. And my sister-in-law Cheryl divorced my brother Davy after twenty-two years, once the kids had grown up and she realised he was only ten per cent tolerable, and ninety per cent tosser.

As you enter your forties, it feels like the bad news overtakes the good. More cheating spouses and tests on breast lumps, and a lot fewer mini-breaks to Paris. I’d seen enough marriages crumble to know the risks.

I suppose I’d always thought, maybe a bit smugly, that Simon and I were solid. Solid as a big, immovable, maybe not particularly inspiring, rock. More Scafell Pike than Kilimanjaro, but still solid.

‘ Mum ,’ shouted Ollie, having walked into the room without me so much as noticing his size ten feet stomping through the hallway, ‘stop!’

‘Stop what?’ I said, wiping my hands on the tea towel. My face was wet. I hadn’t even noticed I’d been crying. I wiped that with the tea towel too.

‘Stop spreading mayo on that chocolate log, because it’s going to taste like puke – are you going senile or what? And are you…crying?’

I glanced down. It looked a bit like a scene from Close Encounters of the Third Kind , where everybody was trying to sculpt a big hill out of mashed potato. Except ruder – because a chocolate log covered in a white creamy substance does look kind of gross.

I scraped it all into the bin and took a deep breath. The tears were still flowing. Even if my brain wasn’t quite processing what was going on, my emotions had kicked in against my will. I swiped my fingers across my face to wipe the tears away, smearing my cheeks with chocolate mayo cake.

Should I tell the kids or not? Was there any point, if it wasn’t real? Perhaps I needed to read that e-mail again. He had said it wasn’t to do with me. That he just had some issues to work through. Maybe he’d go on a retreat to Tibet and fix himself, and all this emotion would have been for nothing.

Maybe I should wait and see what happened. What he had to say for himself. The Simon I knew, the Simon I’d loved for so long, wouldn’t do this. Maybe it was just a rough patch. Maybe he’d come round tomorrow, see me in my finest negligee and realise the error of his ways. He’d come crying into my arms, and bury his head in my heaving bosom…except I don’t own a negligee. Or anything more sexy than a T-shirt from the local garage that says ‘Honk here for service’ across the boobs.

When you’ve been married for seventeen years, have two teenaged children and are almost forty, you’re more likely to be shopping at Mother Malone’s Big Knicker Emporium than Ann Summers. Maybe that was the problem. Maybe I should have been greeting Simon at the door every night dressed in garter belts and stockings, bearing a G&T with a blow-job chaser.

‘Come and sit down, Mum, I’ll make you a cup of tea,’ Ollie was saying, carefully taking the knife from my hands and putting it on top of the fridge. He gently placed his arm round my shoulders and guided me over to the sofa. He’s already much taller than my five foot five, and it’s disconcerting to have to look up at your own baby.

I realised then how seriously he was taking my newfound pallor and altered mental state – he’d actually taken his iPod earphones out, and they were dangling like silver tendrils down the front of his I Heart Tolkien T-shirt.

‘What’s up, Mum? You look terrible. Has there been an accident? Is it Lucy? Have you finally accepted you should have let that priest do the exorcism when you were up the duff?’

His lame attempt at humour both warmed my heart and made me feel even worse. I felt more tears welling up in my eyes, running down my face in big, fat, chocolaty drops, pooling under my chin and making my neck soggy.

I stared into space while the deluge continued, barely able to breathe between sobs, lovely Ollie patting my hand and looking slightly more hysterical with every passing moment.

He jumped up as he heard the front door slam – I don’t think he’d have cared if it was a gas salesman, or a hooded figure carrying a scythe. It was the cavalry as far as he was concerned.

My own heart did an equally big jig – was it him? Was it Simon, coming home to tell me it had all been a mistake? Telling me he was sorry? Telling me to forget all about it? I felt so impossibly weak, so impossibly broken by his proposed absence, that the thought of him walking back through that door was like being zapped by a defibrillator.

‘What the fuck’s going on here?’ Lucy shrilled at us as she stormed into the living room. Not Simon after all. Someone much scarier.

Lucy is five foot eight, most of it legs, and does a very good storm. Hands on hips, she stared down at her weeping mother, fidgeting brother, and the tea towel smeared with the remains of mayo-on-sponge. She narrowed her eyes and threw her head back. Her hair didn’t budge – probably because it was dyed midnight blue-black, straightened, and glued to her head with industrial-strength hairspray.