The letter starts off on the attack and is demonizing. (I know, it is retaliatory demonization, but still not good in a letter.) That said, starting with "W, I love you." It gets good and deep and meaningful. You could be thorough and purge all instances of referring to what she does wrong, but I will not be that strict. You make your point -- she is not perfect. Perfect people don't have affairs. Period. I'd say, go ahead and send it without the opening remarks. If you are going to be that deep and honest, don't drive the reader away first.
Never mind, I see it's sent, and she has no response. That is such an insult when someone is open and honest with you.