Why can't I stop thinking about it?

Trigger warning: Thoughts of SA, violence and experience of sexual harassment

Ever since I meet this "friend" in highshool I started to have these thoughts of being sexually aggressive towards him. I'm not sure if it was because when we meet he said some innapropriate things to me and at the time I was sexually repressed by my religion and parents, so him being the first to say such perverted things caused me to constantly think about him in that way as the "perverted incel" as he would be watching innapropriate things in front of me and say pretty misoginistic things. Making it even weirder that during our 10th grade year even though I had a boyfriend we would have our legs wrapped around each other and I would be placing my feet on his crotch just to see his reaction, disregarding the rest of the students in that class and just having this semi-sexual relationship with him even though we didn't kiss or touch beneath clothes. Furthermore these intrusive thoughts of being sexually aggressive increased when I found out that he is scared of women and I can't say my affection for him increased because I still found him unnatractive and wouldn't date him but after he said that he'd sexually assault me, it *** me off and for a good while snapped me out of that "dream-like" state only to have a strong urge to pin him down while he's crying and sexually assault him, gripping his soft face being the thing that I would constantly think about, that face overwhelming every other thought in my brain and even after not being in contact with him, I still have these aggressive sexual thoughts about him and I don't know what to do, and I don't know if the reason for these strong vivid thoughts is that I really want to do it or if I'm suppressing myself of something else.