Help - One of my friends continuosly brings up my other friend who did some shitty things to her before highschool

Ok so I am friends since the start of highschool with this girl (I'm in college rn) that is pretty shy, introverted, doesn't talk too much etc. yk what I'm talking abt and I started talking to her randomly in 9th grade and I liked her. We became and still are friends and since then nothing really bad happened between us. Not any drama, big fight ever. She has her issues ofc bc she has an unstable household and she constantly chases people who don't give a sh abt her (and I'm constantly trying to tell her that and she kinda listens to my advice ngl), but overall she s a pretty good person in my opinion.

Now comes my other friend that I got to know better in an Erasmus project back in the 11th grade. We were in the same class but we never spoke much, primarily bc i was intimidated by her. She s super cultured and knows a lot of intellectual stuff, philosophy, literature, history, law... you name it. I am also quite a cultured person ms i would say but more like a jack of all arts master of none typa way.

At first I enjoyed my time with her so much cuz i could've went crazy with any subject but over time some things started to show. For example she s really judgy of others, others like me even (I'm gay and an artist in a conservative country so pick a struggle💀 she s also your average heteronomative girl with a bf and i am not judging her rn by describing her like this) but she doesn't treat me as such "bc I'm her friend ig". Still this does affect me bc I AM the type of people she judges, just bc I have intellectual interests and I'm more opinionated abt overall accepted ideas in society doesn't mean I'm different than them. Continuing, most of you will probably say "well, it's clear that u don't like her and you should leave" but I genuinely had nice experiences with her throughout the years. It's just some things that are ingrained in her mind that really piss me off, but honestly she s one of the people who really know what they want and what boundaries to set and when and I appreciate that since I'm also like that and i rarely find people like that, it's just that sometimes she exaggerates.

And now I should start the main plot of this post. Ok so the later friend (whom I'll call Emy) had a "relationship" with one of my classmates (whom I'll call Tina) back in 8th grade, so when they were 14 yo. and together with the first friend that I mentioned (whom I'll call Mary) formed a group. At some point they met up at Tina s house and things got heated up and Tina kinda started to force herself onto Emy and she kind of froze and tried to discreetly push her off and she succeeded. And in the mean time while all of this happened, from what Emy told me, Mary was in the room with them and after this happened she laughted it off. Now Mary told me herself she did some shitty things to Emy in middle school but she definitely felt regretful. Also Mary wanted to be included in the groups of people Tina had around bc other way she would've been pushed out.

Now, Emy told me that she told Mary to cut Tina off bc she felt uncomfortable around her, but Mary told her that she(Emy) can't limit her friend group like this and if she cuts Tina off she ll be a loner. Ofc this was shitty, but rn idk how much can i trust Emy bc, like I said, she tends to exaggerate things. Idk if Mary really told her this with the same words or attitude. Maybe she interpreted it wrong maybe not.

Rn I can't really believe none of them bc I love them both and I can't separate ms from one or other to see this situation more objectively. Emy still feels resentful towards Mary and I get that, but Mary also condems what she did throughout the years to other people and now she s changed. Emy doesn't agree of her change bc she thinks that from the shitty person that she was, she bacame this innocent girl who would do no harm and that feels unrealistic to her.

But I'm also thinking.... At 14 yo witnessing in front of you SH/SA if you even can understand it is harassment, puts you in a fight of flight mode i imagine. Wasn't Mary's laugh basically fawning? If I would've been in the exact position she was I would've probably froze. I wouldn't even think that it's SA maybe

Emy now, evey time i meet with her, brings Mary up and asks if I still talk/hang out with her and sh and I just fucking hate it.... Like ik u hate her, but she s my friend... Pls stop telling me shit abt her bc it makes me uncomfortable asf. I might be the problem here maybe, bc I just don't react in any way other that "I'm sorry this happened to you" " It was not ok of her" but she talks with so much hate like she actively sees her everyday, and they've cut contact 5 years ago. Meanwhile, Mary doesn't mention Emy at all in our convos, bc she s embarrassed she was like this in the past and feels guilty.

I understand that for Emy this was a traumatic experience and that it might've even shaped her as a person, but at the same time I can't invalidate Mary's experience also....

Am I in the wrong? And what should I do to fix this? Tell Emy to avoid the subject? I'm afraid she might judge me