Am I the asshole for making a joke about how my ex best friend slept with the man who r@ped me

So I 16F got into a fight with my former best friend also 16F. It goes way back since I was 11. I was r@ped by my step brother from the age of 7-14. My friend (we’ll call her A) A what had happened to me when I was 11 in 6th grade, I know I was 11 since the r@pist was 16 and only got 6 months probation for it. She then was aloud to come over to my house in the summer of 7th grade. Around the age of 12-13. He would’ve been 17-18 at that time. Soon after she started to come over she developed a crush on R (my rapist) one night she told me she was going downstairs to get some water. She didn’t come up until at least 30 minutes later at first I didn’t think anything of it. Couple weeks go buy and she tells me she kissed him but that was all. I was upset but got over it. Fast forward Years later I started hanging out with some of her friends after i had gotten out of a really bad breakup. She says they were “bad influences” but one of them were her friend. She told me and him that we need to tell her when, where and what time we would go hang out with anyone so we kind of stopped talking. I had found out from this friend (C) that she had actually slept with R that night. I confront her and she started playing victim. Saying she didn’t know at the time. which is a lie Since I told her when we were 11 and she’s claiming to have slept with him at 13. She then goes on to say she never meant for me to find out like this and that she was going to tell me but she didn’t want me to be upset with her. May 1st 2022 the day of her birthday party, we were all joking around and she said jokingly that she hated everyone and I said “you can’t hate me if you slept with my rapist” she got quiet and hours past. She left the room with one of her other friends then Her older sister comes downstairs yelling at me saying I’m a bad friend for making her cry at her own birthday party and I’m a toxic friend. She said that me and A shouldn’t be friends and that if it wasn’t for everyone being here she’d beat my ass. So I then go on to say “how am i a bad friend. Your sister slept with the man who raped me for 7 years and lied to me about it” I left the party after that. I guess no one knew that she slept with him. Fast forward too now, I have a boyfriend and she goes on to tell him that she was 13 and R was 16 when she slept with him. Now people of Reddit if she was born in 2006 and he was born 2001 how in the hell could she be 13 and him be 16? Well she called me a toxic manipulative bitch to my boyfriend once again claiming victim. So I’m just curious am I the asshole for making the joke about her sleeping with the man who raped me.