My Ex Has a Boyfriend

So, pretty much everything that has happened in this story is my own fault. How it all began is when my boyfriend at the time told me he was bisexual. We had been together for 4 years and had been trying for a baby. We had never gotten married because I never liked the idea of marriage. He said he didn't either. He had sat me down and told me he had spent a lot of time trying to accept himself. He said he didn't cheat. Just that maybe all the signs where there, but he ignored them. He comes from a very traditional family. He said he still wanted to be with me. Him coming out was more for him to be honest with himself. I didn't know how to feel. I loved him so much, but this was a lot to take in. I told him everything was okay... But deep down it wasn't. I had this weird feeling he would leave me for a man. Everything that happened after I put on myself. I got uncomfortable with him hanging out with other man. I was always in his phone to see if he was talking to other man. I just didn't trust him, even tho he hadn't done anything for me not to trust him. He did start to get annoyed with everything because I would freak out if he was around any man. He called me toxic... Which at the time pissed me off, but I knew he was right. He gave me a choice. Either trust him and stop acting so obsessive. Or break it off. I chose to break it off. It hurt. We wanted a future and a baby. But I let my insecurities get to me. To this day he is the only man I have ever loved. It's been almost 2 years and we did make up and become on good terms. I did apologize. He has a boyfriend now. The hardest thing was when I found out that had adopted a child they were fostering. Don't get me wrong the kid was cute, but I just figured the parents would get custody back. It's so hard to watch him have a child when we tried for so long. But yesterday was when I broke. They got engaged.... We both said we never wanted to get married. We didn't believe in marriage. And now he is marrying someone else. If he had proposed to me I would have said yes. I will never stop loving this man, but I have no chance not getting him back. My insecurities caused what I feared would happen.... I don't know how to get over the future I wanted now being gone forever. I know it's been almost 2 years but is there anything I can do to fix this?