Girlfriend cheating on me with women, broke it off, should I feeling guilty?

six months in an exclusive relationship with a beautiful girl of 26. found some clues that she was into girls, so i admit i snooped around a little bit, found a bunch of very explicit internet sights visited recently. I asked her about it and she lied, so i left. We argued and she got really upset and then we never talked again. I miss her but at the same time, well i don't like being lied to. My friends are like yeah man that's awesome. it's not awesome because while arguing with her, it was apparent that she did not want me involved in it at all. my questions are did I go to far in getting upset and breaking up? (I didn't yell or anything). Should i feel guilty? I felt like I was her cover, so other people wouldn't know she was into girls.