Reading the letter you are thinking of sending your W seems to me, in its essence, to be a letter of release. What if you revised it a bit, so that it sounded like less of a "good-bye" and more of a "here's what I have have realized about me" letter.
Such a letter would be similar to the one I just sent H. I know your wife has a different psychological background and has different issues than my H, but will she get angry if you are only talking about your responsibility for the state of the R?
I am not advocating that you take full responsibility, just that you own what's yours in the letter, without telling her about what she did. I was amazed by my H's response. Just a thought.
As for the conversation with your son, I think you are a great dad to have raised such an insightful child. I do think it also presents a great "teachable" moment about the act of forgiveness and that we do it not only for the person who wronged us, but for ourselves.
