Aw, hell, I’ll throw my two cents in.
(FTR: I’m 22, male, in a committed relationship. My last relationship ended when she broke the engagement. On the phone. While she was in Germany, and I was in the U.S.)
First thing I want to say is, I see the trend here being that the men say you ought to dump her, and the women say you ought to give her a second chance. The former is a typically male attitude; men are territorial, and can’t stand to see another guy muscling in on “their” woman. And therefore would advise another man the same way they will advise themselves in this respect. To paraphrase several rather rude posters above: “Dump the bitch.”
That, of course, is the easy way out. It requires no thought; it requires no work on the relationship; it requires merely a fight-or-flight reflex, and enough adrenaline to trigger it.
I know that it may be hard to forgive her her indiscretion, but it may be the best thing to do. As someone said above, this will either end the relationship or strengthen it. But if you back out now, you have ended it without taking the time to try to strengthen it.
Of course, if she doesn’t want to do that–if she wants to cheat on you further, or if she was testing you to see what your “limits” are–then you will find out soon enough. And you can then dump her with the clear feeling that she is, in fact, not interested in having a committed relationship with you–she may even leave first. And you can move on without that icky feeling you have now: that if you dump her now, you might have missed something.
I also want to applaud Spider Woman. ‘Tramp’ and ‘slut’ are not words I enjoy hearing thrown around. Personally, I like to class male trash and female trash into one broader category: assholes. All of 'em, male and female. They exist, unfortunately–but a lot more of 'em are men.
(Yes. I dislike men. Perhaps sometime I’ll explain my philsophy…)
LL