I (17M) have a half brother (28M) from my dad. Dad died when I was 4. When dad died my half brother chose to live with his maternal grandparents and ended all contact with me and my mom too. His mom had died the same year I was born (my dad and his mom were divorced). He was never really a part of my life. My mom always loved him and tried to keep him in our lives in some way. Dad's parents helped us do that by inviting us all to parties and encouraging him to accept us as his family and become a part of our lives again. He never wanted to. I hardly know the guy. All I really know is he doesn't think I'm his brother. He tells people he's an only child and never had any siblings and he talks about how he lost both parents by the time he was 15.

My mom has never stopped wanting him to be in our lives again. She has always talked about him and how much he and dad loved each other and how one day she wants to believe he'll realize he loves us too. That dad would never have wanted us to be separated like this. It makes me worry about my mom because she's kinda obsessed and I get that grief is hard and stuff. But he chose not to have us in his life and I think she should accept it. Instead she chases after him begging for him to want us.

My dad's parents put a lot of pressure on him to invite us to his wedding and he did. He even said when he handed us the invites that they got what they wanted and he hoped they shut up about it. My mom acted like he handed it to her with a hug. I was so done with the whole thing when I realized how much work my grandparents had to put in to make him give in and it just seemed so fucking weird and wrong. Why force an invite for people who aren't wanted?

I have said so many times now that I won't go. Mom gets upset and tells me we need to be there to show him we'll always support him and be there. My grandparents told me I can't abandon my mom to the wedding alone and she needs me as emotional support. I told them if they hadn't forced the invites she wouldn't need support. They said he needs to be pushed to do the right thing and it'll probably pay off in 20 years for me.

WIBTA if I don't go?