This happened to me a long time ago, I was depressed for a week or two but then I realized that if my gf really loved me that she would listen to me and not just believe everything that she is being told.. try to talk to her, pull her aside and tell her how you feel about everything. it will be hard but it should be done.. Hopefully your gf will understand completely and give you another chance to prove yourself.
Lovehim501
