Faithfulness

so here's the deal.
Ive been dating this girl for almost two years now. i really do care for her, but we tend to fight as often as we get along. a few months back we had decided to spend some time apart to cool off a bit (but not like we had really broken up, just a 'break). so anway we got back together and the other night she told me that during that time a few months ago, she cheated on me with another guy. i blew my lid when i foudn out cuz i still consider this cheating.

i really care for her and we really do have some great times together (in between the petty arguments), but i just can't seem to get past this.

advice? how should i handle this - would you have felt as though you were cheated on if this was your situation?