<human>: My group of friends are back home from college for winter break, and I just found out from a friend that my best friend took my ex to a fraternity formal this past year.

It's been almost a year and a half since the breakup (end of senior year in high school), but it was a REALLY REALLY bad breakup - nearly destroyed me. Got 3 c's that semester after being a straight A student in high school, cut off communications for a while, fucked up freshmen fall semester of college because still wasn't over it.

Am I overreacting to all of this? Right now, I am really angry more so than jealous because my best friend knows the kind of damage she did to me, won't get into specifics but she fucked me up pretty bad. I am confident that I'm completely over her now, but its just the fact that everyone in my friend group seemed to know except me, and I'm kind of too scared to ask more details about the night. My best friend and I tell each other EVERYTHING, was this something he just thought wasn't important?

Give me a shortened version of the text
<bot>: Best friend in high school took my ex-gf to his fraternity formal, don't know details of the night because too scared to find out, do I have a right to be mad at him?