He is mentally abusing me and lying repeatably

He has been mentally abusing me. He ignores me, leaves me out of imporant stuff, mocking me, threatening to take stuff away from me. I was on a family vacation for 2-3 weeks. I was headed to my room I was staying in after I did some things. When I took my phone out, I got a message from him saying "These girls are hotter then you" and "Your such a good girl, why can't you be wild like these girls?" I had various voicemails from him with girls giggling. I called him, and he called me a bitc* and told me to F off.  I left him for 6 months, but he decides to come back into my life, like he left 5 seconds ago. I tell him to leave me alone, but he just says "Oh no. I'm staying here". He has hid his drug addiction  from me for 2 years, and I had to find out bout it from my neighbor/his friend. I just don't know what to do. I feel like I need him, but I know there is someone else that is way better then him.  Please help!