I said, “You must be Sabine. I’m Delphine. I’m leaving. The party is yours.”

Then I picked up my coat from the hook beside the door, stepped past her into the hallway, and pulled the door closed behind me. Thirty guests. His ex in the doorway. My duffel bag already in the van. The whole thing took about eleven seconds.

Margot was waiting at the corner. I had texted her from the bathroom twenty minutes earlier. We drove to her apartment and she poured wine and neither of us said much for a while, which is what a good friend knows how to do.

Here is what I learned afterward from three different people who were in that room.

He stood at the open door for a moment after I left, and then he turned to his guests with the expression of someone whose careful plan had just collapsed in a direction he had not modeled. Sabine, to her credit and my permanent gratitude, did not step inside. She stood in the doorway, looked at the room full of people, looked at him, and said, “I told you this was a bad idea,” and handed him the wine and left.

She had apparently told him exactly that when he invited her. She had said it would be unkind and he had told her his wife was mature enough to handle it and that she worried too much. She came anyway because she believed him, and she left because she trusted her own judgment more than his reassurance, which tells you something about why they were no longer together.

He called me eleven times that night. I did not answer. He texted things that moved through the stages from confused to defensive to something that looked like remorse but arrived too late to mean much. I stayed at Margot’s for two weeks while I decided what I actually wanted, which turned out to be different from what I had been telling myself I wanted.

We are divorced. That is the clean sentence at the end of it. The apartment was his lease. The van was mine. The tools were mine. My grandmother’s jewelry never left my bag.

I still live in Brooklyn. I still fix leaking pipes, and I am better at it than I was. The wrench I set down on the kitchen floor that night is on my workbench now, and sometimes I think about the sound it made when I put it down, how final it was even then, before I knew what I had already decided.

He asked me once, later, through a mutual friend, whether I had planned the whole thing from the beginning. I said I had only planned to be exactly as mature as he asked me to be. Which was the truth, and also the answer he deserved.