Both of them.

Him.

Her.

With their texts and secret hugs. Treating me like a fool.

A new energy is suffusing me. A new, incandescent fury. Last night I played it all wrong. I was wrong-footed. I didn’t react quickly enough. I didn’t say the stuff I should have said. I keep going over the scene, wishing I had confronted Dan with those texts, that I had shoved everything out in the open. What was I thinking of, waiting for him to confess? Why was he ever going to do that?

So today, I’m taking charge. My husband’s lover may get to do a lot of things. But she does not get to write me a two-faced thank-you letter, laughing at me behind my back. She does not get to do that.

I send a text to Clarissa: Just popping to London Library for research, then google Mary’s company, Green Pear Consulting. It’s in Bloomsbury. Easy. As I emerge from the tube at Goodge Street I’m walking snappily, my legs like scissors. My fists are clenched at my sides. My jaw is tight. I feel ready for body blows.

I arrive at the address to find one of those tall London houses with about ten companies on five different floors and a rickety lift and a receptionist whose aim seems to be to misunderstand you at every turn. But at last, after an excruciating conversation between the receptionist and someone on the phone at Green Pear Consulting – ‘No, she don’t have no appointment. No. No appointment. She called Sylvie. Syl-vee Winter. For Mary. Ma-ree.’ – I’m on my way up the stairs to the fourth floor. I’m pretty fit but my heart is already pounding and my skin keeps breaking out in goosebumps. I feel unreal. Finally, finally, I’m going to get some answers. Or some payback. Or something …

I get to the top and push my way through a heavy fire door. And there’s Mary, waiting for me on a tiny landing, as beautiful as ever, in a grey linen shift dress. She looks shocked to see me, I notice with satisfaction. Not so tranquil now.

‘Sylvie!’ she says. ‘They phoned up and told me someone called Sylvie was here, but I didn’t … I mean …’

‘You didn’t know why I was here?’ I say scathingly. ‘Really? You have no idea?’

There’s silence and I can see Mary’s dark eyes flickering with thought. Then she says, ‘Maybe we should go to my office.’

She leads me to a tiny room and gestures to a chair opposite her desk. It’s quite a bare space – all pale wood and posters for environmental causes and a striking abstract painting, which I would ask her about in different circumstances.

Mary sits down, but I don’t. I want the advantage of height.

‘So,’ I say, in my most cutting tones. ‘Thanks for your letter.’ I take it out of my bag and throw it on to her desk and she flinches, startled.

‘Right.’ She picks the envelope up warily, then replaces it on her desk. ‘Is there a … Are you …’ She tries a third time. ‘Sylvie …’

‘Yes?’ I say, as unforgivingly as I can. I’m certainly not making this easy for her.

‘Is something … wrong?’

Is something wrong?

‘Oh, come on, Mary,’ I snap. ‘So you’re having a secret thing with him. An affair. He’s moved in with you. Whatever. But don’t send me a letter saying thank you for the lovely dinner, OK?’ I break off, breathing hard, and Mary stares at me, her jaw dropped.

‘Moved in with me? What on earth …?’

‘Nice try.’

‘Oh God.’ Mary clutches her head. ‘I need to unpick all this. Sylvie, I’m not having an affair with Dan and he hasn’t moved in with me. OK?’

‘Oh, right,’ I say icily. ‘I suppose he hasn’t sent you secret texts, either. I suppose he didn’t tell you he feels “pinned in a corner”. I saw you talking, Mary. I saw you hugging. So you can stop the play-acting, OK? I know.’

There’s silence, and I can see I’ve got to Mary. I’ve punctured her serene veneer. She looks quite rattled, for an angel.

‘We did talk that night,’ she says at last. ‘And yes, we did hug. But as old friends, nothing more. Dan wanted to open up to me … and I found myself listening. Talking.’ She suddenly rises from her chair, so she’s at eye-level with me. ‘But Dan and I are not having an affair. We’re really, really not. Please believe me.’

‘“Old friends”.’ I echo the words sarcastically.

‘Yes!’ Her face suddenly flushes. ‘Just that. I don’t have affairs with married men. I wouldn’t do that.’

‘What about the texts?’ I fling back at her.

‘I’ve only sent him a couple of texts. We’ve chatted. Nothing more. I promise.’

‘But you’ve met up. At Starbucks. At Villandry.’

‘No.’ She shakes her head. ‘At your house we talked about meeting up, possibly … That’s all. He just wanted to talk to me. Download. That’s all.’

‘Download about what?’ There’s an edge to my voice. ‘About how I’m “nuts”?’

‘What?’ She blinks at me in shock. ‘No!’

‘Stop denying it!’ I erupt. ‘I’ve seen the texts! “Running late”. “It’s ok have distracted S”.’ I make jabbing, quotey gestures at her. ‘“Remember PS factor”. I’ve read them! There’s no point lying!’

‘I have no idea what you’re talking about!’ She appears baffled. ‘What’s the PS factor? And he’s never been “running late” because we’ve never met up.’

I’m breathing hard. Seriously?

‘Look.’ I summon up the photos I took of Dan’s secret phone and thrust them in front of her. ‘Remember these?’

Mary looks down, her forehead delicately wrinkled, then shakes her head. ‘I’ve never seen these texts in my life.’

‘What?’ I’m almost shouting. ‘But they’re to “Mary”! Look! “Mary”!’

‘I don’t care. They’re not to me.’

For a moment we just stare at each other. My mind is scrabbling around and around, trying to find an explanation. Then Mary grabs the phone. She flicks through the photos until she comes to a text from “Mary” reading New mobile no. from tomorrow, followed by a string of digits.

‘That’s not my number,’ she says calmly. ‘Those aren’t my texts. I’ll show you my phone, if you like. You can read the texts Dan sent me, all three of them, and you’ll see how innocent they are.’ She grabs an iPhone from where it’s charging, and swipes it open.

A moment later I’m looking at three texts from Dan, all beginning Hi Mary, and all along the lines of So great to make contact. Mary’s right. They’re all innocent and even quite formal. Nothing like the intimate, casual ease of the other texts.

‘I don’t know who this is …’ She jerks a thumb at the photos on my phone. ‘But you have the wrong woman.’

‘But …’

I sink into a chair, my legs trembling. I feel shoffed. I feel so shoffed, I’m breathless. Who’s this other Mary? How many Marys does Dan have in his life? At last I glance up at Mary, who seems equally perplexed. She’s swiping slowly through my photos, and I can see her grimacing.

‘I can see why you’re … alarmed,’ she says. ‘What are you going to do?’

‘Don’t know.’ I lift a helpless hand and drop it. ‘Dan went off somewhere last night. He said it was a work trip but I don’t believe him. Is he with her?’

‘No,’ says Mary at once. ‘I can’t believe it. He wouldn’t do that. I think more likely—’ She stops as though a thought has occurred to her and I sit up, alert.

‘What?’ I demand. ‘What did he say to you? Did he confide in you?’

‘Not exactly. He started to … but then he stopped himself.’ Mary sighs. ‘I felt bad for him. He’s really stressed out at the moment.’

‘I know he’s stressed out!’ I exclaim in frustration. ‘But he won’t tell me why. I don’t even know where to start. It’s like there’s some massive great secret. But how can I help him if I don’t know what’s going on?’

Mary is swiping through the photos again, reading the texts carefully. Her brow is furrowed and she seems troubled. She looks as though she’s wrestling with a dilemma. She looks as though—

‘Oh my God.’ I stare at her. ‘He did tell you something. Didn’t he? What?’

Mary looks up and I can tell I’ve hit the mark. Her mouth is clamped shut. Her eyes are pained. Clearly he revealed something to her and she’s protecting him because she’s a good person and she thinks it’s the right thing to do. But it’s the wrong thing to do.

‘Please, Mary.’ I lean forward, trying to convey the urgency of the situation. ‘I know you’re his friend and you want to respect Dan’s confidence. But maybe the best way to help him is to break his confidence. I’ll never ever say it was you who told me,’ I add hurriedly. ‘And I’ll do the same for you, I promise.’

I can’t see how an equivalent situation will ever arise, but I mean it. If it does, I will totally reveal everything to Mary.

‘He didn’t tell me any details,’ says Mary reluctantly. ‘Not properly. But yes, there is … something. He said it was clogging up his life. He called it his “ongoing nightmare”.’

‘His “ongoing nightmare”?’ I echo in dismay. Dan has an ongoing nightmare that I don’t know about? But how can he? What is it? What hasn’t he told me?

‘That’s the phrase he used. He didn’t give any other details. Except …’ She bites her soft, pink lip, looking uncomfortable.

‘What?’ I’m nearly popping with frustration.

‘OK.’ She exhales. ‘Whatever it is … it has to do with your mother.’

I gape at her. ‘My mother?’

‘I’d talk to her. Ask her. I got the feeling …’ Again Mary stops herself. ‘Talk to her.’

I can’t face work. I text Clarissa, Still researching, back later, and head straight home. By the time I reach Wandsworth I’ve left Mummy three voicemails, texted and sent her an email – entitled We need to talk!!! – but I haven’t had a response. I’ll go round there in person if I have to. Right now, though, I need some quiet time to digest what I’ve just heard. An ‘ongoing nightmare’. How long has Dan been dealing with an ongoing nightmare?