The guy I was dating went back to his ex

I’m in college right now. I met this guy who was a year older than me but he had a girlfriend. We started dating 5 months after she broke up with him (they dated for 5 years), which I thought was kinda soon. They had done long distance for a year and he cheated on her, but I told him I liked him and couldn’t judge him (maybe a red flag). We saw each other every day for 2 months and I really fell for him but the whole time I was scared of being the rebound but he assured me I wasn’t. He was confusing telling me he loved me but then saying he didn’t want a serious relationship because he was graduating and didn’t know if he was getting a job in the same city, but saying it might be too late not to have something serious. He graduated, left, but we were still talking. He stopped replying suddenly and when I asked if he didn’t want to talk anymore he apologized and said he just didn’t want to hurt me. Now I see videos of him and his friends with his ex and I feel used, even though it might be nothing because I knew they were still friends because they’ve known each other since they were little and their families are super close. I was fine with ending things because he left because I kept the good memories, but now seeing him with his ex just makes me feel like he was being fake the whole time and lying to me about being a rebound. I know I shouldn’t care anymore because he’s probably not thinking about me but the idea that he played with me and I let him hurts so much because everything was great with him. My friends tell me that they could tell he really liked me and he said it all the time, but I don’t know what to think anymore and it just hurts a lot and I feel like I’m never gonna find anything like what I had with him because even though it was 2 months, I had never felt like that in my life before.