Ok so this is going to be a long story but I ask you to bear with me on this one, cause I don't know who to turn to right now, but I have BPD . So CW: self harm, intrusive thoughts about suicide, being cheated on, sex  
I was with my (now ex) boyfriend for almost 3 years, we lived together and I thought everything was going fine, he was very supportive ( I just finished college) and was there for me when I needed him, we talked about things and rarely argued, I go to therapy and sometimes he went with me. So about 3 or 4 months ago he started working 2 jobs which means he was away sometimes even for 16hours per day (he has a child from a previous relationship which he seees 2 times per week and every other weekend for the whole weekend), which was very hard on me cause I felt like I was just there to take up space, we talked about this and decided to take one day (not the whole day but you get the point) per week to spend quality time together, go out, go hiking just you know do stuff together. And then it happened.   
We had a huge fight and I told him I was very angry and don't want to talk about this right now cause I might say things I might regret later, and he said '' if you don't talk to me now about this I am warning you this is going to end badly and I might distance myself''. This is the first time he said anything like that and I told him I was too upset and worked up and I need some space. So we didn't talk for a couple of days, and I noticed he was acting strange so my first thought was I think he is seeing someone else, I noticed he was trying to confuse me on what days he worked far away and where, he started to be possessive over his phone and he turned away his phone when he was typing, but I said it was probably my imagination. I couldn't take this anymore and after a week or so of this I decided to confront him and ask him why he became so emotionally unavaliable, and what's going on and if there is someone else, he was reassuring me time and time again that there was no one else and blahblah, so I had no other choice but to believe him eventhough I knew deep down what the truth was. He was away for a week visiting his family (I couldn't go with him cause I had to turn in my thesis and if there was anything wrong I could have to fix it right away), and when he was supposed to be home he didn't come home so I lashed out and told him I was packing my bags cause I've had enough of him and am going to my mom's place and after a couple of hours he just said I am not coming home if you are there. I begged him to come home and please just talk to me, he did after and hour and he said I am to pack my bags and go, I refused, I was hysterical and crying begging him not to do this and he told me he was done with me and started packing my bags I said I am not going anywhere, I had a huge breakdown and he said he was going to call the police if I don't leave, so I had no other choice.   
I went home in the middle of the night, confused and not knowing what the fuck was happening, and I kept pushing him on the cheating issue and he lied to me about it everytime, I was about to have my defense for my thesis in a week and this was a really bad time (I did it on my own but I was in a dark place), after that I asked him to meet up and talk about this and we went out and acted like a couple but he broke down every single time and I didn't understand why, and he started to go out and I was convinced it was with someone else, so after like 2 or 3 weeks I called him and said I've had enough and it's time for him to confess finally, and he did. I went into a really bad several days long episode of rage, splitting, switching, I relapsed after 5 years of being clean of selfharm and tried to take my life. My episode was so bad I had to be hospitalized for 3 days. I kept going back to him and tried talking to him, I even slept with him a couple of times after that, and I keep trying to get him back, I still love him even after he threw me away like I was nothing, and I have no clue how to deal with this. He told me that he broke off things with her (regarding sex) cause he felt bad and guilty.   
He told me we could be friends and I said ok if you never talk to her again and he said he can't do that and that he wants to give her a fair chance, and I just kept sleeping with him even if he was going out with her because I thought I can win him back, I am very depressed and very anxious every single second of the day, and don't know what to do anymore, he told me he lost all feelings for me eventhought I don't believe that cause he is acting like he cares, checks up on me and so on. He told me yesterday that things didnt work out with her cause he is so emotionally unavaliable, and he hasn't slept with her since they broke off contact the first time. I just don't know how to move on, he is my FP and we aren't officially together for 2 weeks now, but he doesn't want to mend the relationship cause he thinks he doesn't deserve this, and he is going to go to therapy on his own cause of this.   
My question is how do I move on? Do I try and break through his wall and slowly get him back, I really think he is the one and I love him deeply, I just think he started putting up walls and doesn't know how to break them down now. Do I try and talk to him? I don't have the strenght to block him and cut him out of my life but my BPD is getting worse and I am in a really bad place rn. Sorry for the long post I really needed to tell someone about this and get some fresh perspective