Online Harrassment and pregnant

By the way this is the first time I’m dealing with a physcopath. Someone please help me🤦🏽‍♀️so I had this best friend but we’re not cool anymore. And the last time we were cool her boyfriend started texting me, we all became 3 close friends. We all hung out. But I noticed he started getting closer to me and only wanting to call and hang out with me but not his girlfriend.so I got uncomfortable and the person I am I decide to take distance. So a couple months ahead of July of 2020 he gets locked up for robbery. I was confused and decided to cut him off and my best friend would to. So we did when he gets out of jail like 3 months later he keep texting us. It’s December and he harrasing me on Facebook telling me he’s obsessed with me. Hell cuss me out and he acts like I’m his girlfriend. Now mind you I’m already in a relationship and it’s good we’re expecting a baby plans on to marry and this guy knows that. So the guy texts my boyfriend trying to ruin my great relationship that I’ve been in for almost two years now n keeps texting me saying please give me a second chance.

IVE CRIED BECAUSE IM DIGUSTED AND I FEEL LIKE ITS MY FAULT FOR BEFRIENING HIM AND BOT KNOWING HIM. I have told him to leave me alone your not my boyfriend I don’t want anything to do with you. I’m 18 this guy is 21 and he’s pissing me tf off. He knows where I live and I’m scared for my life. This is like fatal attraction movie type stuff but only I didn’t do anything with this guy we were just friends. I don’t know what to do any advice is welcomed