Yeah, you really shouldn't fight to stay with her too hard.
If you were more like, "I didn't fuckin do that shit, if you don't want to believe me, then fine, fuck it, I'm gone. Believe your dumbass friend over me if you want, but I didn't do that shit, and I'm telling you I didn't do that shit. If you can't believe me or trust me then this relationship is pointless." Then walk out and don't contact her. She would probably attempt to contact you in a few days if you did this - she would probably come running back, but if she didn't come running back, then fuck it, her loss, go find some new chicks to fuck with.
That's what you should have done, but I'm guessing you didn't do that, so it's probably too late to save your situation... you could try that though, just say your sick of the bullshit and sick of trying to convince her that you didn't do it, because you know you didn't.
If you were more like, "I didn't fuckin do that shit, if you don't want to believe me, then fine, fuck it, I'm gone. Believe your dumbass friend over me if you want, but I didn't do that shit, and I'm telling you I didn't do that shit. If you can't believe me or trust me then this relationship is pointless." Then walk out and don't contact her. She would probably attempt to contact you in a few days if you did this - she would probably come running back, but if she didn't come running back, then fuck it, her loss, go find some new chicks to fuck with.
That's what you should have done, but I'm guessing you didn't do that, so it's probably too late to save your situation... you could try that though, just say your sick of the bullshit and sick of trying to convince her that you didn't do it, because you know you didn't.