Dear Ex Boyfriends Girlfriend,
Even though it'd be easy to claim total innocence for hooking up with your boyfriend once since you got together, I still feel really terrible. Yeah I was drunk and yes, I was in a completely comprimising position before I even realized what was happening. But I still feel terrible. I have yet to meet a person who likes you and I know there are a bajillion reasons for me to feel like what I did is completely justified, because the reality is that you suck very badly. But still, I apologize. The truth is he is a lying cheating bastard who did it to me and is now doing it to you. And while I really don't like you and I know beyond a doubt (you make it very clear) you hate my very being, you deserve better. Nobody deserves to feel the way I KNOW he makes you feel.
I've been there...it sucks,