Although bent double in agony, Harry made a grab for the phone, but I rebuffed him, continuing, ‘And then, her reply to you: My heart is breaking! I was especially looking forward to unwrapping your gorgeous gift . . . What is the job that is keeping you from me? I have a job in mind too, with the word “blow” in front of it. P.S. Don’t forget to delete this in case Ruby starts prying.’

Silence was now bouncing off the walls. Even the waiters had stopped circulating and had turned to gawp at the slow-motion marital car crash unfolding on stage.

The shock on Harry’s face was intense. He appeared to be midway through an experiment to see how long a person could stay in a wind tunnel. ‘It’s just harmless banter . . .’ he spluttered.

I could see my sisters working their elbows like oars to get through the sea of people to the stage, signalling to their respective husbands to Do something!

‘I wasn’t going to s . . . s . . . say anything till after the party – well, obviously that worked well, didn’t it? So, who is it? She’s listed in your phone under “Stiff Nipples – Air Conditioning”. You talk of an “anniversary”. So how long’s this s . . . s . . . sordid little liaison been going on? And how does this two-faced bitch even know my name? . . . Oh, god.’ Once more I realised I’d been caught with my synapses down. ‘It’s one of my friends, isn’t it?’ I turned back to face the audience and started jabbing my finger accusingly around the room. ‘Which one of you so-called pals has wrecked my marriage? I just wanna know so I can’—I racked my befuddled brain for an appropriately awful revenge—‘pack your tampon tubes with live funnel-web spiders. Is it one of the Yummy Mummies?’ I demanded of my dumbstruck husband. ‘I bet it bloody is! You’re all so sanctimonious, aren’t you? Swigging your kale juice at the school sports day, constantly going on body-cleansing retreats . . . yet unable to survive without collagen injections and wine o’clock. But if it’s a s . . . s . . . s . . . school mum,’ I beseeched my husband, ‘how the hell do you tell them apart, with their identical floaty Camilla dresses, bolt-on boobs and botox?’

I had a vague awareness that I might be drunker than I had realised, and that it would probably be prudent to shut up, but then I thought, Hey, it’s my fucking fiftieth. Why interrupt my journey into self-annihilation? I bent down from the stage to snatch a glass from a surprised guest and drained it in one go. The booze re-ignited my recklessness.