Karen paled even more. ‘He told you that?’

‘Yeah, he told me that’s why you came early, so you could fuck him while I was away.’ I didn’t recognise myself speaking. ‘Christ, why? After all this time? Why now?’

Karen paused. ‘He said it was only one time?’

There is a certain feeling when the worst happens, and the bottom falls out of your world, and you somehow pick yourself up from that and stabilise, adjust. There is another feeling when you suddenly find out this is not the worst, not by a long way. ‘Wh-what?’ I could hardly push the words out of my mouth. ‘It wasn’t?’ My mind scrolled back through the years. University? When Jake was born, and Karen used to stay with us a lot, desperate to get away from her houseshare? When Cassie was born? Weddings, christenings, parties. All of them suddenly covered in a greasy film.

She said, in a flat voice: ‘I slept with Mike the first night I met him.’

‘But that was . . .’ That stupid photo Callum had. ‘That was the night he met me!’ All this time I’d treasured the memory. Oh yes, Mike and I met on the first night of university, inseparable ever since. The next day we’d gone for a walk over Magdalen Bridge in the cold October sunshine, both of us in blue and yellow college scarves, talking about all the nothings of our lives the way you do when you’re eighteen, and after that we were just a thing. Ali and Mike. We had our ups and downs, sure, but somehow we kept going, as all our peers hooked up and broke up and moved systematically between each other’s beds. But that first night, after I’d gone to bed, still a virgin and the worse for wear on four peach schnapps and lime, Mike and Karen had. Done that. I shook my head in disbelief, as if trying to clear water from my eyes. ‘I don’t believe you.’

‘It’s true, Ali. I mean, God, way more off than on, but it’s been years now. If he said it was just once, he was lying.’

I gripped the edge of the sofa. ‘When I was having Benj. When I had to stay in hospital that week.’ Karen had come down, helping to look after Cassie, then just five.

She just nodded.

‘When my dad died?’ Mike had been so sweet to me then, rubbing my back as I cried myself to sleep for ten nights in a row, holding the fort at home while I went north to help my mother clear out the house.

‘Yes. Ali – you realise it hurts my case. If we had a previous . . . relationship. I’m telling you so you know I’m not lying that he hurt me.’

‘But you lied all those other times!’