Deciept and Despair

 Its almost one pm, I'm stressed out and haven't been to bed yet. Me and Gina are fighting...bad. I choked her and slapped her after I noticed that she had unblocked a guy on Facebook who had been trying to fuck her when I first got with her.  

She gave me three different explanations as to how and why she was talking to him again, which means me she lied to me at least two times about  what was going on between them.

I normally don't get jealous or insecure,  but she has a history of being unfaithful, and I caught her lying to me about a guy she's talking to behind my back. She swears she would never cheat on me, but given the fact she lied to me about him i cant believe her.

She wants me to put an app on our phones that will allow us to see eachothers text messaging facebook and call logs to prove shes being faithful, but i cant stand the idea of a relationship that requiers us to spy on each other, besides whats stopping her from getting a second phone she can use to talk to other guys.

She can't accept that by lying to me about him she's made it impossible for me to believe that she's been faithful to me.  I don't know what to do, I'm hurt and don't wanna accept that she's most likely fucking around on me.

I hate that I put my hands on her, but at the same time I feel like she had it coming to her.