Before my 19-year-old son di3d, he donated his heart to an 18-year-old girl — after the transplant, her mother handed me a letter from my son that began, “Mom, there’s something you need to know about her.”

And at the bottom she wrote: She’s not asking for a mother. She’s asking about the woman who raised her brother.

Her brother.

I rang her that evening.

And Katrin, who I have now met eleven times myself, which I find funny in a way that is not really funny.

We are not friends. I want to be accurate about that, because people want us to be, and they ask, and I can see them wanting it.

She is the woman my husband was with while I was up at night with our baby. That does not go away because he is dead and because her daughter has my son’s heart.

And she has never once asked me to say it does.

She does not come into the house. In fourteen months she has come in twice, both times because it was raining hard enough to be silly. Otherwise she waits in the car, or goes and does the shopping and comes back.