AITAH for not being able to go to my friends birthday party because she invited my old bully?

i, F20, have a friend that’s turning 21, and having a fairly large birthday party. i found out today that she invited the girl that was incredibly cruel to me for years. i have trauma because of her. she’s part of my ptsd. she psychologically damaged me for years. i cannot be in the same room with her. i promise i’m not being dramatic. i saw her two years ago at a party and ran off to the bathroom cried my eyes out and almost threw up. my friend claims she didn’t know she bullied me. but she was there and i swear i used to always talk about it, but maybe i’m misremembering how much it was. i want to go to my good childhood friends party so bad, she even invited my boyfriend which is kind and will be fun. but i’m serious when i say i can’t be around this girl. i’ll be sick. AITAH?