I [18 F] and my boyfriend [18M] ended it because I texted my while we were broken up when I thought we were never getting back together

This is quite hard to explain, but I want people’s input on what to do and if I’m in the wrong,, not that it matters but I would like to know. So me and my ex boyfriend had many issues in our relationship, we were both extremely jealous and he was upset about my past when he found out I have talked to other guys years prior to us being together. This was always hard for me to talk about with him because he would get upset at me and just angry and I’m quite a passive person so I would just apologize and try to change the discussion. Overtime I had enough of it and just broke it off a lot of the time, but he would always over apologize to me and I would always come back because I loved him. We went on breaks multiple times, but on one of these breaks, I found out that he texted his ex girlfriend while he knew we had the intentions of being together again. I blew up at him and didn’t want to hear anything he had to say so I just blocked him and that was that. A week later I called him and asked him for clarification on why he did such a thing and he told me “I was trying to better myself and understand what I can do to be a better person/ partner for you”. Back story with this, everytime I would try to break it off he would tell me he’s going to be better and treat me right. This made me very angry because why does it matter what went wrong in a past relationship while you’re with/ on a break with someone that has a completely different perspective than that last girl if that makes any sense. I heard him out, stupidly but we were still on a break. Before I reached out to him, I became Friends, key word friends with a guy on instagram while he (my ex) had my account on instagram and found out about him and got completely angry at me and I explained that it was just a friend thing but he kept saying he was flirting with me and that he was done with me and maybe we can be together in the future. This completely broke me, as I really thought I was going to marry this guy. Then, one night stupidly me and my friends prank called my other ex, I’ll call him Gerald and me and my friends were just messing around with him. But then he figured out it was me, and I kept texting back and forth with him even while I was trying to get back with the ex I thought I was going to marry. I broke contact with Gerald after Gerald gave me a ride home one day when the buses weren’t running anymore. I felt disgusted with myself because this ex Gerald put me through so much and I just felt ashamed with myself with just seeing him even if it was just a ride home. I blocked him on everything. This was in the span of maybe less than a week. Then, the ex I wanted to marry, the one this post is about, me and him hung out and really talked about everything. Like deeply. He spent the night at my house for a couple days and in the span of those days, he went to my graduation and met some of my family. On the night of my graduation when I was asleep, he went through my phone and saw the messages with me and Gerald. He now wants nothing to do with me and even took back his sweater that I loved. It feels unfair to me because he also texted his ex, but he just had a better excuse than me. That might be fucked to say but it’s just how I feel. I really need input on the situation, there’s more to it but I feel like I’ve said enough for now. I really hope this isn’t the end to us but it’s really starting to feel like it is because he’s now following other girls on instagram and such. Please help Reddit I don’t know what to do. How do I go about this?

TLDR: need advice