Wishing I knew before.....

A while before my current boyfriend and I got together (at 4 months now) I had casual sex with a friend of my ex fiancé's, Aaron, obviously we knew one another and I knew he was a womanizer but I was in a state where all I wanted was casual sex and he seemed safe, I knew him after all.. But as it turns out I didn't know him as well as I thought I did.... I found out today that about a week ago my friend Gaya's husband CJ showed up at his door at 6am, screaming at him and got into an actual fight.. Apparently my friend told her husband that Aaron wouldn't take no for an answer and he forced himself onto her.. and she's not the first girl he's done it to. He's apparently done it to 3 of my other friends (Brittney, Michelle & someone else, can't remember now, too much shock). I feel sick. I want him dead. I was supposed to go with my ex to Aaron's birthday party tomorrow for drinks at the house, but if I were to go knowing what he's done.... I'd likely break my hand punching him. The 4 people I now know of makes me wonder how many other girls he's done this to...the thought disgusts me. Since the beginning of may I've been doing significantly better, I've had little to no depression or anxiety, I record my mood every day to watch for trends and to see how I'm doing overall, up until today I've been great. I wont let this get me down or keep me down, I didn't know I was having sex with ... a rapist ... I fear had I tried to say no I could have been a victim as well, but when I went over to hang out I had a feeling sex would be had and I was fine with it, but never once did he pause to ask if it was okay, he just did what he wanted...and he definitely asserted control in the situation, it was significantly rougher than my day to day sex life is and had I protested and he continued the same way...it would have been traumatizing.