Daughter wants to invite brother to her graduation

This is all very messy. It happened a long time ago but I still have hard feelings towards the situation. I had my daughter when I was 20. My baby daddy was 23. When I was 21 and he had just turned 25 he cheated on me with my mom who then was 45. Me and my mom always had a bad relationship. She blamed me for losing my twin brother when she had us. She always tried to do things to get a rise out of me and she slept with my baby daddy just to prove she could and got pregnant with me and my daughters brother Jesse. So because my baby daddy and my mother are disgusting I now share a brother with my own daughter. Jesse is 16 and I have no real relationship with him. I understand this isn't his fault but he is a reminder of a very painful time in my life. I completely cut my mom off and my daughter would have nothing to do with her and Jesse at all except when her dad does get her, Jesse is sometimes over there so while they are not close they have met and have somewhat of a relationship. My daughter is graduating and asks to invite Jesse. I asked does she really want her uncle brother as her graduation and she said she would just like everyone there. She also wants him at the graduation party. I have no relationship with Jessi. We met one time and I didn't even speak to him. People can say it happened a long time ago. That I need to move on but before you start with that can anyone on here say their baby daddy cheated with their mother and got their mother pregnant? I have avoided being around Jesse as much as I can. Why should I have to relive my trauma