My Gf Broke Me Bad!! Need 2nd Opinions!

Ok, so just thinking a lil to much and wanting some 2nd opinions. I dated this girl, 1st date I made her cry over how well I was able to read her emotions, with in the 1st 10 minutes of laying in the bed and talking. Then went to the local bar and was shooting pool, A biker guy walked up and tried to hit on her and she was having nothing of it since it was our 1st date. He tried to ask her to come and meet the rest of the gang, she said no, several times. Then he grabbed her and pulled her off the table and I walked up and threw his hand off and said the lady said no. Had a lil bit of a mouth match but nothing after that after he realized I had just stood up for my date. She fell for the chivalry of that as well as the emotional connection. Things were great, sung her songs on the guitar, gave her space when asked, and she would come running back by the night came. She was a ex college student, who had a past that wasn't to impressive, but I chose to look past it as the connection and enjoyment of each others company was just so well. Around 4 weeks into the relationship, she went back on her word, said I was going somewhere with her, spent over a hour getting ready, and then she changed her mind last second. Really pissed me off/made me upset, its just a really big thing to me to trust the words my partner says. She started to make this a reoccurring thing, and I got tired of it, as well as some slight mental abuse. So, I broke up with her, within 5 hours after she took off to her home town over a hour away to hang with her friends, she started blowing my phone up with texts. How she loves me more than anything, understands the pain I have been threw with her, and how the woman I always wanted out of her was here, please take her back. She drove, at 3 am to my house, over a hours drive. She got here, cried on the floor, telling me how her whole life was a **** up, and she needs me in her life and maybe wants to marry me. Said she was gunna sleep on the floor if it wasnt in the bed with me, just as long as she was around me. I took her back, after all everything I wanted out of her was finally infront of me. Well things were great happy go lucky, showed up at her house, surprising her with food and nice things, a couple of spikes of issues but nothing that lasted more than a few hrs. Then around a week and 2 days after her begging on the floor for me. She says she dont want to be with me, says, her best friend "a woman" had kissed her and told her she wants more than friends, and how she wants to be with another best friend who is a guy. How she still thinks about being with other people, etc.. etc.... So I left it at that, went home trying to figure things out, I decided to fight, after all I am a competitor. My desire to win is 2nd to none and I asked her, would you rather me quit or try to be with you and win you back. I was told to try, so I did, we hung out a few times a week, acting like we were never split, same ol kiss same ol sex n laughing type of things. But, she started taking advantage of it, using slanderish type of language toward me and how to describe me, for example I am a dog since she told me we arent together and I still act like we are. Like she isnt leading me on to believe that, since she was still throwing me those lips and *** when around each other. Well, I was still stuck on that night, when a person does something like that at 3 am and crys for 6 hrs for a person, there has to be something there. That was mainly the reason I was still trying, and she never truly denied her feelings that night, except the want to be together for ever since she had already broke things off. Well I had got tired of the bigotry, and decided to tell her we ant gunna talk no more, she started to cry, saying I am a good man and how she wanted me in her life. Shortly following that she had told me how shes off making out with her best friend "woman" the last few weeks she had been telling me to try. She leaves and well I had alot of mixed feelings, one side says, don't quit you love her and the other says go off on this ***** and tell her how you feel now that shes done you so wrong. I decided to go off, she had a past full of evilness, my fault for thinking there could be a upside to a person with such a history as you know, having a boyfriend at 19 (shes now 23), having sex with his friends on the side, as well as his step dad while no one was home, and to this day have no regrets, and enjoy those things she has done. So I went off, she went off, Then told me that night that I held onto for so long was just her way of seeing if she could take a good man and make him go back on his mandates to be treated better, her words, she told me what I wanted to hear and it worked hook line and sinker, then a few days later texts me at 12am how shes hookin up with that step dad at the hampton, then at 7am send pictures to prove how the night went with him n to never see me again. how do I trust or love again?