How to leave a toxic relationship a

I've been with my boyfriend will ex boyfriend for 3 years however we shared good moments but 90 % percent of the time it was bad i was always there for him when something went wrong he spent 9 months for being around someone who had a gun he just came home in may even before he got locked up he will say mean things to me but its like it got worse i was here when he father died which he really wasn't that close to him i also had a bond with his mother but i notice she was abusing pain pills and would flip on me he also started hanging his friends more than ever they will be with him all day and every time i will call he will tell me to stop calling him he tells me i look like a tranny also how i don’t have a big but i had two miscarriages by him one minute he tells me he love me then he tells me to leave him alone he is also abusing cough syrup and pain pills and gets high with his mother time to time everytime i try to tell him something positive he tells me to shut up i'm doing to much and i'm not his mother he only talks to me now 5 in the am his friend brings girls around and he talks to the girl i ask him why is he doing this he tells me he is single but if i don't text him for two days he is calling me from block numbers telling me he miss me and it's the same thing over and over also if we get in a argument he tells me he having sext with other females and how they look better then me then he will l lie on his father grave and say he said that to make me mad but i know he is lying i also know that he is selling drugs i find out im so stressed out i can't even get up and go to work i really need advice i have no one to talk to im in college i dont smoke and i work and i get treated like crap