Pit, I need help. Female troubles.

Okay, so my girlfriend started bitching at me, saying I was all over another girl, and told me she didnt love me and **** liek that, so she goes to a basketball game alone, all pissed off. My friend who happens to be there sends me a text and says shes all over another guy, this furiates me. So I say, ****ing figures. Apparantly it was her on his phone. She dumps me.

First. I was never on any chick.
Second. Come to find out she was joking about that whole subject.
Third. Is it wrong of me to feel blind sided?
Fourth. I DID really like this girl, but she has a depression/commitment issue. I try to help her, and it made her madder.

I want her back Pit. Any tips?