I think this letter will not help your sicth at all. Write it and post it but don't send it. All those things you described do them through changing not through words.
I know you are in pain grr, I really do but I think that letter will have the opposite effect of what you want. He knows how much damage he is doing but you reminding him of it could cause him to resent you.
I think right now #1 goal is to get your mind right, the blow up with your H just happened a few days ago I think two so give it some space and time.
