I just saw a thread on here by someone and realised I'm in the same situation.
I've always been attracted to girls and recently had (but no longer) a girlfriend.
Within the past couple of years though, I've started to become attracted to guys - both in general and some of my friends
I told my ex-gf (...no I broke up with her :P ) that I was bi, but I've never told anyone else. In fact, I kind of split up with my gf because I really fancy one of my friends - after I stayed at his house and he said he'd like to experiment when I asked him (he went to sleep straight after that though.... but that whole thing's another story - i.e. nothing happened ).
I don't know whether to go for it or to keep testing the waters. Girls still really turn me on as well life is confusing!