I'm a 25 year old male, and I've been in love twice. Once when I was younger with my highschool sweetheart. That lasted from 15-22 years old. And at that time I was undiagnosed. It ended miserably bad and we had awful fights all the time. I do not know how we made it so long. But I just thought it was because we were young. But later found out it could have been largely because I had BPD symptoms that I didn't understand. (I still don't understand them) After that, I dated a few other females, and had a lot of flings. I never had any fights with any of those females I dated for short periods of time(1-3 months), but most of the time I felt those relationships never worked out because we had zero connection, or because I wasn't ready to settle down again. But at 23 I joined the military, but was quickly discharged for a suicidal remark I made to the wrong person. I was then diagnosed with BPD, childhood PTSD, depression, and I had a substance abuse problem. I thought it was all bullshit. So when I got out, I went home, got a job, and just drank myself to the point of dying every day because I felt like I had no one and nothing at this point in my life. Until I met M. M was 18, and I met her when I was 24. The first night we went on a date, I knew I was in love with her. She says the same thing about me. We connected so well and I had never been so happy in my life. She did everything in her power to help me stop drinking, she got me to quit cigarettes, she got me free therapy, she legitimately took care of me. She saw I was broken, and she so badly wanted to fix me. I still am in love with her because of all of the effort she put in to try and help me get better. But again, the same thing that happened in my first relationship, happens in this one. After all the girls that I dated before M and after my first love, girls that I had never fought with or had arguments or problems with,  and thinking I was more mature and that I was in better shape for a good healthy relationship, I managed to break this one apart even worse than the relationship with my first love. I mean we had arguments that were bizarre and so crazy that I can't believe M and I made it 8 months. But alot of those arguments I barely remember what I said. I hardly remember why we were even fighting. But anytime I felt threatened or insecure by something she did or said to me, I would just almost go into this defense mode that when I was in it, I would do anything or say anything to hurt her before she hurt me. I really want to stop this. I just don't know how. I'm tired of losing people I love. If I could get M back I would be happy, because she is someone I really enjoy. But not if I'm going to keep hurting her like I have been. What can I do? What should I do?