He broke up with me.

So I've been talking to this guy for over a year. We finally got together after hanging out constantly for 3 or 4 months. He's the first person I've actually ever liked, he's my first boyfriend, first kiss, he's so many firsts for me. His friends became mine, I'm friends with all of his friends, I even started weight lifting with him. (An important note is he just got out of a 3 year relationship and got right into one with me. He is also one of my brothers friends.) The first month we were together everything was pretty much great. He says I'm the sweetest girl he's met. (We go bowling every week) So when we are bowling another girl goes and he seems to me wants to hang out with her and he said they were friends but I was still jealous because it felt like he was giving more attention to her than to me. So I asked him about it and he gets upset and says that I don't trust him. But I did I just wanted him to give me a little more attention than her because I was his girlfriend and not just another person there. Another thing is he said our relationship was killing his friendship with my brother. He broke up with me a few days ago. He says the reasons are that he's been in a relationship for 3 years, im too jealous and my brother. Im so heartbroken, but I guess I kind of understand that he needs to find himself? He wants to be friends but it's hard to even see him.  I aready miss him so much. I'd appreciate suggestions and thoughts!