Am I doing the right thing being with her?

Ive been dating this girl since October she was dating my friend thats how we meet but he cheated on her with her best friend so I decided I would make a move I did and we were making out and I loved it the next day she went back to her ex and had sex with him the whole time she was texting me... I got over that cause we werent dating plus at the time I had a gf to but that had dwindled down to nothing cuz that girl was cheating on me and we dated for 5 years.... so I went to NC with her we had sex but when I came back home my friend told me that she was hitting him up after that trying to get with him but when i confronted her she knew nothing about it note this is my friend for a long time he has had a gf for a long time very reliable person just a little slow. anyways I got over that i decided to bring her and her friend over to my friends house somehow she got the idea I wanted to have a threesome with me and my friend cuz he was joking around with it she was pushing me in the room and he was like cmon she was like cmon I didnt want to at all i told her i had to go to the bathroom and i left running but i had so much heart for this girl i dont know what it was her smile her laugh her everything just pulled me closer to her esp her beautiful eyes.... anyways she ****** him then I made her tell me but she said its cuz i left and she was drunk... still dating my gf... this girl tells me shes pregnant from nc im like ok probably a best bet is to do adoption she was like no im having it i thought about it for a while and i really liked the girl i wanted to be with her i wanted to have the kid for the first time in my life i was ready and willing to open up a spot in my life for a child and i wanted to give the child the best life possible so i dumb my gf and get with her the day i get to her house she goes on her period... found out she has psos? i think thats how its abbreviated im not for sure so she cant have babies. she lied just to be with me in a weird way i thought that was cute and stalkerish but it worked btw this girl was stalking me around town but again i thought it was kinda cute... so where together i lived at her house her family is crazy so i moved home around christmas she bought me an xbox360 for xmas and gave it to me early for some reason i had bought her a wrist thingy like 600$ but wasent gonna give it to her till christmas... I saw on her fb something about her getting off work a couple days to do something then out of nowhere she breaks up on me on dec 18 a week before xmas and she comes and gets the xbox... what the... anyways i cried up till xmas eve but i knew id be happy on xmas so i was trying to keep a smile it was just really hard...she calls me on xmas night saying she wants me back she doesnt wanna be alone on xmas... I said you know what I threw your gift away and you took mine back so xmas is done with you but ill call you the day after... she cried and went about her way spending xmas with her friends cuz there family is to ****** up to do the xmas thing... i called her on the 26 got to her house... she had already had guys blowing up her phone had already put herself online on more than one dating site. I was heartbroken I was like how can you say all this stuff about loving me but you cant wait 2 days... somehow I got over that. she changed her phone number quit her job cuz her mom was goin crazy and moved in with me getting a job over here it was going fine... but her job was stressing her out so much making her go crazy on me i dont know wtf was happening... we spent a week on vacation i took her on her first vacation it was so much fun but she was losing it down there to... we get back she starts going even more crazier i had to tell her to leave and get like bipolar medicine but we can still date that was fine she wanted to go back so she did now shes back at her old work with malesters and idiots her mom lets her bf smoke crack in the house her brothers on drugs and shes bi polar its all messed up... soooo last night she tells me shes going to her gayfriend brians house... she wouldnt pick up from 11-3 so i thought to my self those are clubbing times then she was like yea we walked down the boardwalk i was like swear on my life you didnt go clubbing cause we had made a very strong promise to not do that to each other knowing the only reason you go to the club is to dance with someone or hookup... she couldnt swear on my life and she said she went in to a drag club to donate for relay for life... but didnt dance i made her swear she didnt dance she said ok ok i did some kind of shuffle.... swear on my life you didnt dance with anyone she was like im done with you fighting with me and hung the phone up but not before making me feel like im the jerk cause im upset that my girls walking the strip going to a club and dancing right after telling me she would never ever do that to me... NOTE I HAVE BEEN COMPLETELY FAITHFUL to this girl I want a grown relationship