Broke up with girlfriend/fiance of almost 3 years, still living together. Stay or Go?

Hello everyone, I'm turning to this forum for some help on making a hard decision. I met my ex fiance about 3 years ago on a dating site. We hit it off immediately and according to her that was the 1st time she slept with someone on the 1st date. She was staying with her friend after just moving here from AZ. They got into a fight about a week after our 1st date and we were so head over heels for each other that I told her she could just move in with me and she did. I lived about an hour away from where she was staying. I bought her a cheap car, helped her get employment and things were going good. Other than the fact that her son was living out of state with her mom still and she hadnt seen him for a year. Fast forward about 4 months and I was so happy that I asked her to marry me and she said yes. Things up until 6 months were great. I dont know what happend after that other than maybe the thought she was getting married started freaking her out. She had dated many of what she called assholes and I was her 1st all around decent guy. At this point I cosigned for her to ugrade to a decent car instead of the junker. She said shes been cheated on by all of them. 1 with her sister. She started jumping around jobs,going months with no job while I paid for everything, she started making frequesnt trips out of town to see her friends that I was never allowed to join her. We started arguing alot. I was starting to see the bipolar/depression come out very strongly that she said she had but leaves untreated. She would love me like no other, we'd have great sex all the time then before i knew it, she'd be mean and nasty for seemingly no reason. I didnt even know why we were fighting half the time. I just kept thinking we will work thru all of this like any other couple. Well, it came down to be almost a year into the relationship. No wedding date set, lots of issues, and I was getting fed up. The last straw was that she went out of town again instead of staying home and spending time with me and my daughter that was with me that weekend. I was offended about it because that started becoming a habit. We fought and she left out of town anyway for 3 days. She was set to come home and make it in time to watch our favorite show together before starting back to work for the week. She calls and says shes gonna stay over another night adn that was it, I told her if she doesnt come back as previously planned that she could move back out there. She refused to come home and so i packed her stuff up and told her to take it with her when she got home, she didnt have much. She came and got it, seemingly emotionless while I was holding tears back, then left. She didnt wanna talk it out, she was ok with leaving. This break up lasted about 2 months. In that 2 months we talked but only saw each other once for a hook up. She would stop by when I wasnt home and leave me money for her car payment and phone and insurance. I dated one girl after the break up that she was extremely jelaous of, she told me she wasnt dating anyone. Things went sour with the girl I briefly dated and her and i started hanging out alot again and decided to give it another go. I laid out some rules before agreeing to get back with her though. I would be introduced to all these friends and she would stop ditching me for weekends away with them all the time, there would be no lies or deception, and she would try to get the bi polar medicated, she would commit to getting her son here with her and stay at a steady job. She agreed. I knew she was messed up but I wanted it to work so bad because when things were good, they were really good. Our interests, the sex, or music tastes. Everything was amazing sometimes. Well one night early into this, she gave me her phone to hold while we were at a party. It kept going off and up to this point I had never invaded her privacy but I was curious as to why her phone was going off so much. Come to see that there were 2 guys texting her that she had been having sex with during our break up. One was some new guy she met at a bar and the other was someone she called her "Bro", her buddy from where she would go stay all those weekends before. She was telling him how she would love to have his baby and other deep romantic stuff. I was surprised because I trusted her when she told me he was nothign to worry about. I confronted her and we got into a big fight. We left and went back home and didnt talk the rest of the night. The next morning she got up to take a shower and must have been on the computer because she left her facebook up. I couldnt resist and went thru all her messages. I came to find that she had been reaching out to her ex talking about moving in with him out of state in AZ, I found that her "Bro" had been hanging out with her those weekends and she wasnt with her friends all those times, and that he had been trying to get her to leave me the whole time. I was furious. When she came back in the room I was still sitting there and I told her, I know everything now. I wanted answers, I wanted her to leave, I wanted her to stay, it was all messed up. We calmed down and I said to stay with me, you will need to cut all ties with these 2 ex's, especially the "Bro". She hesitated but agreed because she loved me and wanted to be with me. Things went back to being ok again for about 4 months, still no weding plans. She never seemed to care to talk about those plans much. But I finally come up with the money to go get her son while shes out of work again. At this point we got our own house rental together. We travel to GA where he was staying and bring him back to PA. I thought this would make us complete as a family and she wouldnt be so depressed she didnt have him anymore. We set a wedding date finally and I made a facebook event page and invited everyone to give a heads up as it was gonna be a destination wedding. I then told her to invite all her people. She refused and wasnt excited and it seems like I was the only one excited. It bothereed me alot. Well, a few weeks later shes acting shady and I was getting used to the signs this time around. I installed a data logger on the computer and found that she was again talking to the "bro", this time expressing her undying love for him and how she wishes they didnt have a miscarriage (this was a new development for me she left out of the earlier convos) and that she wanted to see him badly. She was back to work while I read this and I waied til she got home to ask her what the hell was going on after I just did all I did for her. She says she didnt know and she doesnt really feel that way and shes so sorry and that she only loves me. I said ok, giving her yet another benefit of the doubt, saying that if i ever see her talk to him again we are done, I wanted full access to her phone at all times. She agreed. We go about another 9 months and things were rocky. I was always wondering and checking her phone and facebook. Constantly waiting to find something. She either kept it erased well or was actually leaving him alone. But about 2 months ago I saw her messaging her friend that loves by the 'bro" asking if she can get a 3way call with him so i wouldnt find out, she did that and I woke her up. Told her i dont know what we are but I want my ring back now. She gave it back after we fought about it some more. The next morning we talked and i told her this shit needs to stop and asked why hes so important, she doesnt know, she just misses him. I told her that the ring was sitign on my dresser and that she could have it back when she trusted herself to take our relationship seriously. In these last 2 months, Ive kept asking her why she hasnt put the ring back on, she just tells me shes still thinking about things. To me this is unnaceptable so I push the issue more a few days later. We were talking about the lottery I played and how I hoped I would win and become a millionaire and be super rich, she blurted out that if that happend she would marry me the next day. A few hours after that convo I ask her again why she doesnt wanna be engaged and marry me? She tells me I'm rushing her into marriage...this was about a week ago. 3 days ago I looked in her phone to see she unblocked the "bro" and was messaging back and forth with him and also a new guy I have no clue of but saying flirtacious things to him as well at the same time. She told the "bro" that she didnt give a **** about my feelings and she was gonna reblock him in 48 hours so i wouldnt know they were talking. Obviously I found the messages, I said nothing to her about them for about 24 hours. In that time she attempted to delete the messages not knowing that I know already. I finally bring it up, telling her I deserve better than that, that we are done for real this time and that there needs to be plans to either find some way to win my trust back or one of us needs to move out. She gets really apologetic, cries, starts loving on me then proceeds to start acting like we are together still all the while knowing we arnt. We had sex again last night. Still havent talked about it again yet. Im so torn because I love this girl so much, we have so many things we love to do together, we invested so much time together,and her son even calls me daddy. Neither of us are financially stable right now so either one of us moving out is gonna take some time but in the back of my mind I'm wondering, can this be fixed? Is she always gonna be so dishonest and devious? Can she ever keep a promise? Can I ever trust her again? What do you all think?

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Alos, thank you for reading all of that, was just trying to be as thourough in the situation as possible.

She's right about one thing; you are rushing into marriage like it's the band-aid that's magically going to fix things. Ask yourself - why do I want to marry someone who has been repeatedly dishonest, who cannot commit and who doesn't take the relationship seriously? Why is she there? I think because it's safe - because you're safe. Because you offer her the stability which she can't offer herself...but that stability is built on something very unstable - no matter what you build, if the foundations are rocky, it'll topple down eventually.

If she has bi-polar (which is a serious mental illness) then what is she doing about it? It's not a word you just throw around in the wind; you get help - you see a psychiatrist, a therapist...you get on medication. So that's another thing that seems to just get pushed to the side, without any real conclusive effort.

As for your own sense of worth...where did that go? It seems to me that you have a lot to offer; you can be faithful, kind, generous...but every time you say 'I've had enough', you end up with her again - not because she's changed, you know she hasn't. It's because it's what you want to believe.

Your love isn't enough to keep this relationship going.