WIBTAH if I tell my brother that I don't like his gf as a person?

So we are all in our 30's and I'm the oldest sibling. Our family is very close. Me and my brother had divorces at the same time about 5 years ago. He's been dating this girl for a couple years. I'm always one to make friends with ppl and try my best to connect with them. I've always made an effort to get to know his gf, but about a year ago he messaged me stating that although we have both expressed (me and his gf) wanting to know each other better, she felt animosity towards me bc apparently I was a little cold with her when she was out waitress and I accidentally called her by my brother's ex wives name once and felt terrible. The names are very very close btw. But still felt friggin awful. I reached out to her and apologized. But since then we have not made any effort to be closer. She is close to the rest of my family as she works at the restaurant my parents own and my sister manages.

Okay, still no issues, until a few weekends ago. I have a regular small town bar I go to every other Friday. She showed up because she knows the cook. I was very friendly, helped her with the digital jukebox, introduced her to ppl, etc. There's this one 15 year old kid who is a regular. Pool player, family atmosphere, it's not abnormal. He is a class clown kinda kid. I was like hey, lemme introduce you to my friend (brothers gf). She was really really mean to this kid. I apologized to him and his brother many times after my brothers gf left. I felt terrible. But now I've made the decision that I don't like her. I don't think she's a nice person. Should I even tell my brother? Or just ignore it?