Why do I still have feelings for an abusive ex

Hi, I dated a guy for 4 years and I’m 20. Our relationship was instant love. He was everything I wanted. We built a special bond and I ended up losing my virginity and everything else to him. He was my world. Slowly things got bad. We went from seeing each other every day to never. Arguing about everything, him calling me names or hurting my feelings on purpose, etc. basically things got really bad and abusive. Mentally & physically. Though he never punched me he would squeeze me as hard as he could (he was much larger and on steroids so crazy strong). He would throw me around, push me around, and some days if I went over and he got mad he wouldn’t let me leave. He left bruises on my body, compared me to my own sister and to other girls he slept with, told me to kill my self too many times to count, would tell me he’s cheating and then blamed everything on me. He made me feel horrible about myself. Somehow I thought there was still love there bc we’d have a bad week then a really good one where we were so in love. It was a toxic cycle. I cried pretty much everyday. I never felt loved or enough when I did everything for him. He did so much to me but I loved our good days. Made me feel like that was the real him. We broke up 3 months ago and I have not talked to him since. He tries to contact me nearly every day and has started showing up at my apartment. I’m not ready to talk or see him bc I know I’ll be right back in the cycle. He knows how to manipulate me and what to say. About 1 month into us being broken up he went to jail for almost a month. I didn’t answer any of his calls. The whole time I found out how he lied to me about everything and I’m pretty sure he cheated. Everything I thought of him was a lie. He didn’t love me but when things were good it sure felt like he did. He keeps sending long messages saying how he’s changed and it hurts bc all I ever wanted was him. I wanted to marry him but he hurt me so much. We’ve never been apart this long and it sucks bc hes said all these things before and he probably doesn’t mean it. I guess I just don’t get why a part of me still wishes it would have worked when he did me so dirty and made me cry more than he ever made me smile... everything he is telling me is everything I begged him for, for 3 years.