I've been re-reading this thread. I feel sort of pathetic for not having left my girlfriend yet. So far, I've only decided to give myself time before deciding whether to break up or commit to reconciling. I keep thinking that I'm just a week away from ending it, but I still haven't.
Anyway, I don't expect anyone here to have any new advice for me, really, but I still appreciate the advice I've been given thus far, and I wanted to give an update.
When she first confessed, I thought that I'd be in shock for a week or two and that I'd be back to normal after that. Nope. I've been getting better, but much more slowly than I anticipated. I keep discovering new ways to think about it that knock me on my ass for hours at a time. I keep thinking that my story is not nearly so bad as most that I read here (not married, no kids, no decades of history). But on the other hand, neither of us had ever had sex with anyone else, and it was so counter to the image of who I thought she was, and it happened while I was making plans to propose. So I can forgive myself for taking it so hard. Oddly enough, I felt better (i.e. less crazy) after seeing more and more people using the language of "trauma". Once I started thinking in those terms, it made more sense. I have triggers. I have flashbacks. I spent a month telling the story over and over, trying to fit the puzzle pieces together. I'm not weak or crazy, just traumatized a little. It's not "okay" but it's normal.
My girlfriend has continued to make an effort to support me and figure this out. She got "Not Just Friends" and read some other material about infidelity with me. We've spent some time talking about her issues in therapy. She offers to talk and listens when I tell her about my anger and pain, and she expresses a lot of remorse. A few times, she's gotten caught up in her own loop of worry and despair about whether I'll leave, and she ends up mired in self-pity. That's not cool, since it leaves me high and dry in my moment of need, and our therapist has been trying to address it, with mixed results. But it's been something she struggled with for a while, so I don't see it as a sign that she doesn't care about me. Then again, if it gets bad and she's just incapable of supporting me through the healing process, I might want to leave regardless.
One new wrinkle that I suspect you all will hate: she's going on another long business trip soon. Her company asked her to go, and she came to me to ask if I thought it would be okay. At the time, I figured that I'd either be much better, or we would have broken up by now. Also, I was only thinking about whether I trusted her not to cheat on me. So I told her it would be fine, and that she should go, and that I wouldn't let it be the thing that destroys our relationship. Stupid. Stupid! I shouldn't have said it and she shouldn't have listened to me. Now it seems likely that it's just going to be weeks full of triggers, while I'm left alone with my thoughts. We'll end up talking over crappy video calls on hotel wi-fi, just like we did when she was having the affair. Part of me thinks I should just ask to skip the calls, and take this as an opportunity to get space away from her and the relationship. But I don't know. It seems bad no matter what.
At this point, I still feel like it's really unlikely that we'll work out in the long term. But I don't want to break up with her and tell my family about it unless I'm really sure it's what I want to do. And I'm not sure. Sometimes I look at all the doubts I had in the past, all the times we almost broke up before, all the terrible details of the affair, and I think that it's obvious that I should just break up and start over. But I can't just do that. I don't know what's really true, because there's a competing version of this story with a happy ending: We had a good relationship for years and years. We had some doubts and some communication problems, but instead of letting them break us apart like some couples, we were committed to the relationship and went to therapy to work on it. And things got better, and we were happier than ever, just as I believed when I was making plans to propose. Then, thanks to naivety and vulnerability and a confluence of circumstances, she cheated on me. But she realized it was wrong and told me about it, and neither of us gave up on the relationship. It was a hard process, but through it, we became closer than ever. And when we finally did get married, we did so confident that nothing could tear us apart, because we were willing to work to build something strong and beautiful.
Right now, I don't know if I believe that. I might. But I don't want to do anything drastic until my mind stops flipping from one extreme to another every couple of hours.
In the meantime, I am ready for the pain to stop. I've had my fill, thank you very much. I'm ready to move on to the next phase. Please. Except, I don't seem to have any control over the speed of this process at all. If I thought that breaking up with her would prevent me from feeling this way, I think I'd do it, but I don't think that's the case. I think it would be a whole painful thing in its own right, with some new flavors of pain and some old ones all mixed together into a delightful cocktail of shit. In the short term, there is no happy option. And I'm angry at her for that, but I also think she's honestly trying to help, to offer me a happy future with her. If that's real, I don't want to throw it away in anger. If we're both going to come out of this as wiser, better people, and if I can trust her not to do this again, then I don't want to fall prey to the sunk cost fallacy. The affair happened. It's irrevocably a part of my past. But whatever. That shouldn't affect my decision except insofar as it changes my expectation of the future. The future is all I can control. I'm trying to focus on the future, but it's not easy when the present is so hazy. Ugh. I'm ready for this feeling to stop.