Would you be upset/sad

So I’ve been dating the same guy since 9th grade. In 10th grade, he cheated on me. It literally crushed my heart so bad. It messed me up so much, I STILL have night mares about her and I hate to admit it but I look at her socials all the time. ANWAYS, me and my bf got back together once we graduated. We are now 22 years old. I just went on snap and saw my bfs cousin who he is very close to, IS DATING THE GIRL HE CHEATED ON ME WITH. They were posting a lot of selfies and it just brought back a shit ton of bad memories. It killed me that I knew my man is going to see all the pics and videos of her and him together. My stomach hurts. I cried actually. I don’t want to see her at family functions or have to hang out with her. I’m scared and uncomfortable. Ugh. Idk what to do. Am I being over dramatic? Would anyone else be bothered ? Please no mean comments. I suffer with really bad anxiety.