Honestly, I had planned on just lurking again, but I just read through the whole Schwedentod story. Dude, I'm so sorry that happened. I really don't know if there's anything I can tell you to make it better. I've been in a similar situation before (the details of which I won't get into again), but suffice to say, it was of about the same magnitude in a shorter time span. Now, I'm still with the same girl, and that was a little over two years ago, so I do think it's possible to work through things like that.
That being said, I think that everyone here knows I'm a bit ... erm, vulnerable? naive?... something of that sort, and so it's rather unsurprising that I eventually forgave her, but I can tell one thing - if she is honestly sorry for it, and I mean that kind that you can see in her eyes, and if this relationship really is a big thing, then I'd try to work on it. However, there is that point at which one has to just walk away. I can't tell you where that point is, so I'll leave that to everyone else, but regardless of what happens, I'm sorry man. I hope things work themselves out for you in the future.
~kov.