I sexually abused my ex girlfriend and I don't remember it..

I think I raped my ex girlfriend, she said I did and that she was scared of me. The problem is I black out at night. I will do things at night that I don't normally do, I do thinks and not remember it in the morning I hear voices at night that I know are not there, I talk to my self and other's in third person. During on of my third person moments I messaged my ex and when I mentally woke up she claim that I raped her. That's the reason she left me, part of me thinks I did it, I don't remember doing it at all she says I am not the same person at night. I get angry all the time I feel like I did something.

Though you do not remember you should trust your girlfriend on this. I do not think you self mutilating is going to help, though I am thankful you are trying to be accountable. It sounds like you foremost need psychiatric help - though I'm no professional so cannot offer a diagnosis here. Are you currently receiving help for your mental health? Otherwise, I believe you can combine unwavering, morally serious accountability with a genuine degree of self-compassion. Please take a look at this zine and think about how you might follow its instructions:
http://www.phillyspissed.net/node/36

Best,
Sprock