I think my kind hearted friend isn't being kind to me

So lemme give some context first.

I started my 11grade in a diff school so everything was new and fresh i had only two friends at the start but it became a group of 6 half year through. One friend from that grp let's call her Y. We hung out and talked more often because she sat near me (seating arrangement) everyday. The thing is Y is a misandrist, homophbic and overall a bad person. But im not a confrontational person so i only said things like "that's wrong" and" no...". Let me be clear we both or atleast she played pranks like normal friends and joked as such. So one day during a substitute lecture i took her pencil fronta her and was like haha imma give this to our other friend. Idk why she got mad over THIS threw that pencil when I gave it back after a min and stopped talking to everyone in the gc. 3 or 4 months later she told others that the reason she stopped communicating with us was because we didn't appreciate her or treated her good. Mind u she got mad over EVERYTHING and threw tantrums EVERYDAY. And reason for these would be smyh stupid like she was gonna say smth and our other friends said smth before she could. Or make a completely normal joke (she used to make jokes on our friends weight, looks and what not we didn't joke Abt anything like this btw). Ofc i was hella mad and told everyone the truth.

Now another friend from the same gc (which consist of 5 ppl since Y left). Is O.

She's a very kind hearted, understanding person whose been through much. Ik this and i support her through everything. I was the one who taught her to stand up to herself if ppl were mean or made comments. O wanted to help Y be better but it backfired ofc.cause Y has a victim mindset. O after a while gave up on Y cause she's hopeless. Everything was fine ther other 3 with me and O had fun and it was great. Mind u out of all 5 of us O gets the worst marks despite studying a shit lot. Another friend from this same gc A one day said out loud infront of strangers to O that she always gets Negative marks (we have negative grading system). And she should be careful with it. O was embarrassed because it made her feel stupid. O told me i agreed it was mean and I told A . A is not a bad person so I told O she didn't mean it. A apologised and everything is good. Fast forward a week or two later we get a msg from O on the gc . O says she wants to stop being friends with everyone including me. I was heartbroken because I never said or did anything that would make her feel disrespected or stupid. Apprently A and other friend T told O that she should change her board( from cbsc to hsc . Principal talked abt changing boards for whoever got less marks). Even tho O said she wanted to try for cbsc. This made her feel like she's stupid and that everyone in the gc thinks so too and downgrades her. I talked with O as to what did i did? To which she was like oh you went to the principal with T and A and didn't invite me(we went for study tips and guidance). I was like we talked Abt this in lunch infronta everyone in the gc and only A told us personally she wanted to come. I said I'm sorry and that I thought otherwise. Btw she wasn't this mad even when Y straight up told her she's dumb and invalidated her when she got SA'ed ( again I was there with her and supported her here). She didn't mention anything Abt breaking friendship with her. But not suddenly she wanted to break friendship when it comes to us.( Because self respect was not considered she claims). I agree they are wrong but why is two similar incidents in which one is wayy worse getting different responses from her. Worst of all why did she included me in the breaking friendship thing? Despite me supporting her through everything, helping her feel better when she had episodes , lifting her self image and helping her stand up for herself. I get dumped to this. Like wtf do i do now