AITA for not telling my cheer captain that I slept with her cheating ex bf?

I (22M) have been a part of my school’s cheer squad for 3 years, since I was a freshman. I’ve never been someone to form super close bonds with most of my teammates, I am close to only a select few and the rest aren’t people I socialize with outside of our sport often.

My second year, when I was 20, a girl named.. we’ll call her Tyler (18F at the time, 20 now), joined the squad. She was pretty driven, professional and talented, especially for being a freshman. I respected her but all in all we didn’t interact much for a little while.

However, she actually became friends with my sister, (who we’ll call) Marissa and the two of them became kind of close. She was in Marissa’s friend group, so we would see each other frequently outside of cheer. We still never really talked much, so I didn’t consider her a friend.

Tyler had a boyfriend at this time, we’ll call him Brick (20M at the time, 22 now), who was a part of the group of guys who hosted a lot of hangouts, parties, things like that. Parties I was often at. I knew they were a thing, but again I wasn’t really involved in Tyler’s personal life, I only knew about this through Marissa. When I learned of their relationship, I had no interest in getting to know either of them, so I didn’t really think twice about it.

That changed when Brick approached me at one of the parties (the ones I mentioned before) and practically threw himself onto me. Oh yeah, I’m openly gay, pretty much everyone who knows of me knows that which I don’t have a problem with because who gives a shit? Anyway, he flirted with me, which I initially brushed off as him just being charming but eventually, it became physical.

I can’t lie, I didn’t reject his advances because he’s hot and I was at a party, I was trying to just have some fun, but I didn’t realize the hole I dug for myself. Long story short, we hooked up. After we did, he told me not to tell anybody, DL college guy, big woop. I agreed and we just kinda moved on with our night. I didn’t think it would even matter to be honest, he wasn’t the first guy who acted like this, he wouldn’t be the last, but it matters now..

Two years later, Tyler has been promoted to primary team captain (she was co-captain the year before) and I still haven’t ever told her I slept with her ex. She knows he cheated on her but she doesn’t know he cheated on her with MEN. I don’t want to out him, because as far as I know, he isn’t out but I do feel underlying guilt for not telling her. I just don’t know that it’s my place to do that, especially since she’s moved on and has a pretty great boyfriend from what I can tell.

Maybe I shouldn’t have done it, but with how long relationships in the first semester of college (especially in Marissa’s friend group) last, I didn’t think it was that big of a deal.

AITA?