I have only read that letter so far, not your whole thread. I will respond now about the letter, and then go back and read more.
I like it. You talk about yourself, not him. You don't accuse him of anything, or call him names. You are optimistic about your future. You are self-confident, not needy. My only caveat to to be sure that you can really live by those words. Once you say them, you will be expected to stand by them. I see you just found out about his OW. Are you really ready to let him go?
