My (31F) brother (29M) married my ex-boyfriend (30M). How do I cope?

My parents announced a few days ago they were hosting a family reunion at their place in another city. I haven't gone because I took advantage of the invitation to stay home and have a morning alone with myself.<br><br>My mom called in the middle of the afternoon to check on me and asked about my plans for next month. I asked what was happening next month and she was shocked I didn't know. Apparently my brother and his *wife* were going to visit and they've invited all the family over. I inquired about who his wife was. I knew he was seeing someone but they hadn't mentioned marriage. My mom was speaking in a weird tone so I knew something was wrong. She said his wife was someone I've known for a while. I thought it was weird but I thought it was maybe a cousin or friend I forgot about. My mom finally told me his wife was Jamie, my ex-boyfriend.<br><br>Jamie and I dated for three years. We started dating our last year in college and we broke up three years later. The reason we broke up was because I caught him cheating. He tried to get me back but I didn't want to continue with him. He's been begging me to take him back for five years. I haven't had any contact with him except for him asking me repeatedly if I was going to take him back or not. I cut contact with him last year because I couldn't deal anymore.<br><br>The reason why this hurts so much is because my brother and I used to be close. He was my only sibling and I considered him my best friend. That was until he moved out and we lost contact. He only started talking to me again two years ago and we've all been trying to get closer as family.<br><br>That's why I don't understand how he married my ex. My parents said they started dating a year ago and Jamie proposed a few months later. My brother didn't tell me and neither did Jamie. They kept it a secret until my parents told me. Now I'm wondering where to go from here. I'm hurt by Jamie because he cheated and I'm hurt by my brother because he knew how much Jamie hurt me. I feel like my brother took away my peace and closure. I'm going to have family reunions and I'll have to come face to face with Jamie. My parents said they wanted us to get along but I don't feel like I can. My mom keeps saying I should forgive and move on because it's been years. But I don't feel like I can.<br><br>How can I move on from this?