As someone who sent a letter, I would say to wait a good while. I wanted to do it for me. But, I wanted to be sure I was in a place where any kind of reaction from him would do me no harm. And truthfully, I wanted to be heard, otherwise, really, what's the point?
While you are detached, you still are feeling hurt and angry at times. And your h is nowhere near ready to "hear" you so you'd just be spinning your wheels.
