please help me!!

ok guys, so i broke up with my boyfriend for maybe a month ago. we had been together for maybe 2 weeks. we had been together before for maybe 9 months. but that time we ended up in october so we did not talk to each other in 6 months. he was like a fkn psychopath the first time we were together. he did'nt want me to hang out with my friends. (especially not guys) he hacked all my social media and took away all the guys from my snapchat and read all my conversations with my friends. He also said that he would kill my very best friend just because I had told him what he was doing. but I thought he had changed so I took him back. (i know it is fkn stupid) he was the cutest boyfriend ever during the first week, but then it turned out that he had not changed at all so I told him I wanted to take a "break" and that we shouldn't meet for a while because I didn't feel well. He got like really angry and started post shit about me on his my story. but now under the time that we hasn't been together I've met another guy. he is the nicest guy I have ever met and he is absolutely wonderful. He treats me like a princess. but now my ex want's us too be together again, I don't want too but I'm so scared of him. please help me. (sorry for my bad english I'm from Sweden)