Breaking up and staying away

So a few months ago, I met an amazing guy at a party. We really hit it off and things were off to a great start. A week after we met each other he wanted to date, I agreed but later on I decided to say never mind and to just take things slow. He didn’t like that so I broke up with him. That same day I went back and got with him. 3 weeks after that I gave him my virginity. 1 month in and he told me that he was in love with me, I kind of felt pressured to say it back, so I did. Then we had a serious talk and I decided not to tell him I love him anymore, that upset him as well. To shortened the story, in just 2 and a half months this man has managed to mentally break me down and emotionally abuse me. He told me he wanted to die if I left him. Everything was always my fault. He was always the victim and he never did anything wrong. So when I broke up with him for a third time, he told me I would never find anyone to have sex with me like he does & treat me like he does. He has said a lot of crazy shit to me and I still go back to him. How do I stay away ? I’m only 19 and he is the first real boyfriend I’ve ever had. I don’t know how to leave and stay gone. Please someone give me some advice !!