I was screwed over by the "love of my life"

Miranda
I had a boyfriend over a span of about two years. We were always on and off. I think we were a little toxic for each other but I never would let myself accept that. I had never had a boyfriend in high school and he was my first one/first real serious relationship and it was already my junior year. Well we were on and off throughout those two years. Every time we were "off again" he would run to his ex and fool around and one time another girl completely. Well the most recent time we had broken up once again, he fooled around with her but I never knew about it. About a month or two later we were slowly fixing things again. She comes to his work and tells him she's pregnant. So then we are shaky but after about two more months we got back together this past January. Well February my birthday was the 8th and our school marching band left for Disney world the 9th. The 10th he gave me a promise ring. After we got back from Disney though, I was just filled with trust issues and I couldn't handle it. He would go off on me and stop when he realized I was most likely leaving and he was manipulative and I couldn't trust him around her and they had both lied to me in the past. Things finally ended for good when he ditched me for my senior prom and decided to take her because we had a falling out. But he tried to come back into my life about three weeks after because I slipped an apology note into his guitar case in the band room. It wasn't to get him back it was just to say sorry for what I had done. Then he tried to be friends and get close and wanted to work on being together again and I finally got him mad enough to block me on everything and stop speaking to me. It has now been about four or five weeks and I'm okay with it. A few days after he blocked me, he made it to where I was unblocked on Facebook. When you're blocked on Facebook neither can see the others profile. So I'm wondering if he unblocked me but set it to where I couldn't message him so he could still see what I'm doing or something. I know this doesn't really make a lot of sense and I'm sorry. I just need opinions because I am okay and all, but I just want to know where I went wrong. Why I can't trust guys. What's wrong with me that no one wants me anymore. I just want to understand. The picture is of me and if I could just figure out what is so wrong and why God put me into something that ruined me.. I would love to know.