It’s not an admission – not quite. But I know her well enough to know that it might as well be. She’s not protesting any more.

‘Ten years. I’m slow,’ I say bitterly. Bitter, not just because my mistake ruined my own life, but because if I’d been a little quicker on the uptake, James might still be alive. ‘Why did you do it, Clare?’

She reaches out her hand to me, I flinch away, and she says, ‘Look, I’m not saying what I did was right – I was young and it was stupid. But, Lee, I did it for the best. You’d have been screwing up both your lives. Look, I went round to see him that afternoon – the guy was shitting himself – he wasn’t ready to be a dad. You weren’t ready to be a mum. But I knew between the two of you, neither of you would have the guts to take the decision.’

‘No,’ I say. My voice is shaking.

‘You wanted it to happen, both of you.’

‘No!’ It comes out like a sob.

‘You can deny it all you want,’ she says softly, ‘but you were the one that walked away, and he let you. All it would have taken was one text, one message, one call – the truth would have come out. But between you, you couldn’t even manage that. The fact is, he wanted out – he was just too much of a coward to make a break for it himself. I did it for the best.’

‘You’re lying,’ I say at last. My voice is hoarse and choked. ‘You don’t care – you never cared. You just wanted James – and I was in the way.’

I remember – I remember that day in the school hall, the hot sun streaming in through the tall glass windows, and Clare saying laconically, ‘I’m going to have James Cooper.’

But instead, he became mine.

‘He found out, didn’t he?’ I stare at her pale face, her draggled hair silver-white in the moonlight. ‘About the text. How?’

She sighs.

And then at last she speaks what sounds like the truth.

‘I told him.’

‘What?’

‘I told him. We were having a discussion – about honesty, and marriage. He said that before we got married he wanted to get something off his chest. He asked, could he tell me something – and would I forgive him? And I said, yes, anything, absolutely anything. I said I loved him, that he could tell me anything. And he told me that at that party where we met up again, his friend had been interested in me – we’d spent all night flirting, I remember. I gave this friend my number at the end of the night – and James said that he found the piece of paper in his friend’s pocket, and kept it himself. He told his friend that I wasn’t interested and instead, he texted me, said that he got my number off Julian, and did I want to go out for a drink.’

She sighs and stares out of the window.

‘He said it had been eating at him all these years,’ she carries on. ‘That our relationship had started with a lie, that it was his friend who should have ended up with me. But he said that Julian was a womaniser, and he’d done it partly for selfish reasons, but partly for me. He couldn’t bear for Julian to string me along, screw me, and then dump me. He was expecting me to be angry – but as he talked, all I could think was that he’d lied and cheated to get me, bent his own scruples. You know what James is like … was like.’

I nod. The movement makes my head swim, but I know what she means. James was a contradictory mix – an anarchist with his own rigid moral code.

‘It was strange,’ Clare is speaking slowly now. I think she’s almost forgotten about me. ‘He thought his confession would make me love him less. But it didn’t – it only made me love him more. I realised what he’d done was for me, for love of me. And I realised that the same was true of me. That I had lied out of love for him. And I thought … if I can forgive him …’

I can see it. I can see her twisted logic. And her one-upmanship: you have done this for me, I have done worse for you. I love you even more.

But she fatally misunderstood James.

I sit, trying to imagine his face as she confessed what she’d done. Did she try to justify it to him, as she did to me? He wasn’t ready to be a dad – she was absolutely right. But that wouldn’t have swayed James. He would have seen only the cruelty of the deception.

‘What did you say to him?’ I say at last. I am light-headed with tiredness and my body feels strange and disconnected, my muscles like wool. Clare looks just as bad – her wrists seem thin enough to snap.

‘What do you mean?’

‘You must have told him something else. Otherwise he would have rung me. What did you say?’

‘Oh.’ She rubs her temple, hooks back a lock of hair that has fallen over her face. ‘I can’t remember. I said something about … you’d told me to tell him you needed time alone – that you thought he’d screwed up your life and you didn’t want to see him. He shouldn’t ring you – you’d contact him when you were ready.’

But of course I never did. I went back to school only to take my exams, and ignored him steadfastly. Then I moved away completely.

Part of me wants to smack him for being so stupid, for being taken in so easily. Why didn’t he overcome his scruples and just call me? But I know the answer. It’s the same reason I never called him. Pride. Shame. Cowardice. And something else – something more like shell-shock, that made it easier just to keep on going, not look back. Something momentous had happened in our lives, something we were totally unequipped to deal with. And we were both dazed from the fallout, trying not to think too much, feel too much. Easier just to shut down.

‘What did he say?’ I manage at last. My throat is sore and croaky and I take another gulp of tea. It tastes even worse cold, but perhaps the sugar and caffeine will help keep me awake until morning, until the police come. I am so tired – so very, very tired. ‘Afterwards, I mean. When he found out.’

Clare sighs. ‘He wanted to call off the wedding. And I begged and pleaded – I said he was being like Angel in Tess of the D’Urbervilles – you know, when Angel confesses to adultery but then can’t bear it when Tess says she had Alex’s baby.’

We studied the book at GCSE. I can still remember James’s impassioned condemnation of Angel to the class. He’s being a fucking hypocrite! he shouted, and got sent out for swearing in front of a teacher.

‘He said he needed time to think, but that the only way he could ever even try to forgive me was if I told you the truth. So I told him I’d invited you to my hen party, so that I could tell you then.’ She laughs then, unsteadily, like someone suddenly seeing the point of a joke. ‘It’s just occurred to me how ironic it is: I always thought hen-dos were completely lame, and James spent ages trying to persuade me to have one – and in the end he was the one who persuaded me, just not for the reason he thought. If he hadn’t kept going on about it, I’d probably never even have thought of all this.’

I understand now. I understand completely.

Clare could never be in the wrong. Someone else always had to take the fall. Someone else had to take the blame.

Did James ever really know her? Or did he just love some illusion of Clare, an act that she presented to him? Because I know, from twenty years of knowing Clare, that his plan was never going to work. Hell would freeze over before Clare would admit to something like that. Not just because she would be in the wrong to me – but because she would be in the wrong to everyone, for ever. I could not be expected to keep quiet about what happened – it would have all come out: ten years of lying and deception and, most humiliating of all, the fact that Clare Cavendish had had to resort to this to get her man.

She must have known, too, that James’s decision was on a knife-edge. I don’t know what he said to Matt, but it was clear that if he was prepared to talk about his distress to other people, it must go very deep indeed. And he’d made no promises to Clare – only said that he might be able to forgive her if she confessed.

I didn’t think, knowing James, that he would have succeeded.

No. Clare had everything to lose by being honest, and nothing to gain.