How to stop my boyfriend from harassing and intimidation without involving my parents?

I was in an intimate relationship with a guy. After few weeks, we got in a relationship. I wanted to breakup because it didn’t feel right and I thought I wasn’t ready for it. I told him since I’m unsure there could be future cheating. We broke up. After which I realised I can’t let him go and I wouldn’t cheat on him so we patched up. But again, things didn’t feel right. He seemed too controlling. He had a problem w who comments on my pictures, who I follow, who I talk to, people I was involved w before him. So I wanted to breakup again. He didn’t let me breakup. He told me you wanted to patch up and now i can’t end it since I’ve already said I like you and all that. He made me feel guilty for wanting to breakup. So I didn’t breakup. After this I still couldn’t stay with him, I told him again that I’ve personal issues with myself that I need to deal with, please let me go. He didn’t let me go. He told me his mental health is suffering and I shouldn’t break up, that he will breakup on his own. So I didn’t breakup, continued being a girlfriend. He never broke up. Everytime I wanted to breakup, he would degrade me, question my character, humiliate me and made me feel guilty. I had told him certain things about myself to him in privacy, about my relationship with other guys but now he’s threatening me that he will show my parents all those chats, that he will show the screenshots of us being in a relationship. He’s jus doing this to make me suffer. Yesterday he called my parents and told them I was in a relationship with him. I thought it would end there. But it didn’t. Today again he mailed me and told me how he has evidence that I tortured him, that he will spill the beans of my sexual relationship with other guys to my parents. I don’t know what he wants and how to stop him without getting my parents involved. He calls me a slut, a whore, a call girl, degrades me by saying I should suck cocks and show cleavage to get attention from people, that I follow people on Instagram to sleep with them. He even made a fake account impersonating a model to talk to the people I follow on Instagram, when my friends asked him to stop texting me, he got more provoked and asked me to ask my friends to apologise to him. I don’t know what to do anymore. I don’t want my parents to know all this. Please help me.