It's been about two months since the incident, and lately, I've been feeling ok about it, like i have a future, like my GF and I have a future, etc. And then I remember what happened, or my GF says something about it, something she doesn't even mean to be hurtful, and I'm transported back into the swamp that is self-doubt, self-loathing, and a complete lack of hope about where everything is going. I see the OW's face on facbeook or something (i don't like this new Facebook feature that means you see everything your friends like. It makes blocking people impossible) and I just feel like complete shit. I hate myself for it, and for everything else I've done to screw up my relationship. I don't know. It's just hard, sometimes. It's hard a lot of the time. 
One day at a time.