“I’ve come straight from the police station,” I said. “I phoned them up and made an appointment to see a detective. Before, I’d mainly seen this female police officer. I suspect she was assigned to me to hold my hand and calm me down as a sort of amateur therapist. This time I made sure I had a proper meeting with someone who had the authority to make decisions.

“I’m going to be honest with you, even if it makes me seem crazier than you already think I am.” I paused and waited for Judy to interrupt and say she didn’t really think I was crazy, but she didn’t, so I continued. “It would have been much easier to prove Greg had had an affair with this woman, and in fact I did find that proof, or at least I thought I did. Are you going to ask what the proof was?”

Judy seemed confused. “I’m not sure it’s really my function,” she said.

“It was a note written on a menu, a menu for a particular date, referring to that date. It looked like evidence that there really had been an affair and that somehow he’d managed to conceal it from me. It should have been a relief, and maybe it was. But I’ve since found out . . .” I felt a rush of horror, as if an abyss had opened at my feet, at the idea of telling Judy the details of how I had found out. “I won’t go into the details, but suffice to say that I now know, without any doubt, that on that day Milena couldn’t have been sleeping with my husband because she was sleeping with someone else. And discovering that left me with a problem—two problems, actually. The first was that I just couldn’t give this up and get on with my life. The second was that once I trusted Greg again, the proof got much harder and more complicated.”

I wanted to be as honest as I could, so I told Judy about how I had constructed the charts, how I had cross-referenced them and how, this morning, I had wrapped them up in a giant folder and lugged them into the police station. I had been taken into an interview room and then I had unwrapped them in front of the startled gaze of the young detective. I had taken him through the most important details while he had consulted his own pretty skimpy file.