How to not go back to an ex

Tldr; My ex continuously crossed my boundaries. For some reason I still am fighting myself to not go back to him after he texted me yesterday. How do I stay strong, and does anyone know why I’m even considering going back in the first place?

I (F20) and him (M22) were only together for a little over a month. During that time he took me out on a “date” once then pestered me to go back to his place which I didn’t. From that point he’d invite me over by saying we’d watch a movie which never ended that way. I won’t lie, at the start I was fine with our relationship being mostly sexual because I was curious, but after like two weeks I wanted to slow that stuff down. I’d say I was tired, that I just wanted to hang out, I’d try to start conversations with him about his day, and every time he’d push for something sexual. I straight up said no to him going down on me and he said ok, and then literally just did it. He ended up taking my virginity (which I didn’t want him to do, I kept trying to stop him from kissing me and I said he was hurting me and I was hyperventilating and crying immediately after seeing all the blood) a week before Valentine’s Day, and then he proceeded to ignore me on Valentine’s Day and when I brought it up he said it’s because I didn’t text him first. He was a shitty guy, so please someone explain to me why he texted me yesterday and I am having to remind myself constantly to not go back. Maybe I liked the attention? But I get attention from other guys, why do I want it from him. It’s not the sex stuff either, I didn’t like it and tbh I don’t think I ever want to do that stuff with anyone after what happened. I’m not that insecure, I’m happy with how I look and the friends I have. He never bought me anything or took me on dates so that can’t be why I want to go back. I literally had a panic attack two weeks ago because I saw him on campus, and I go to sleep on my floor because I can’t sleep in my bed anymore. Please someone help me understand this insanity