Don't be too hard on yourself. You're only human after all. What's done is done. I agree with hhh, maybe it was a good thing - now he knows you won't tolerate his behavior.
As far as the letter goes I can not believe he denies writing it! Wow. That is unbelievable, actually astonishing.
Keep taking care of yourself and check in when you can so we know you're alright.
Take care.
Me: 39 H: 39 S: 15 M: 18 years Bomb: 6/3/09 H moved out: 10/15/09 H moved back:5/30/10