Advice on my brothers wedding

So my brother is getting married in a few months and he is inviting my mother, well long story short she was EXTREMELY physically, mentally and emotionally abusive and I left at 14 and never looked back only dealing with her when she’s gets bored and starts family drama. Anyways I told her she would never see me or my children who she’s never met. My question is am I selfish for not going to the wedding?

No, not selfish at all. Your, and your children’s, mental health is much more important. Tell your brother why you can’t attend and that you’d love to celebrate the day with him and his spouse before or after the event.