Leaving an emotionally abusive relationship.

Hi all. I've recently broken up with my boyfriend of two years. I'm hurt and confused and left feeling as if it was my fault. My boyfriend has always suffered from mental health issues, such as depression and anxiety and I believe there is an undiagnosed personality disorder there too. I've always been very supportive of him and understanding of this. However, his problems are worsened by drug and alcohol abuse. The way he has treated me in the past 18 months or so has been awful. He is insanely jealous to the point he constantly questions any interaction with the opposite sex, doesn't allow me to have male friends and causes an argument every time I go out with my friends. I used to be a very social person but I know I feel isolated and alone as I have stopped seeing my friends just to save myself from arguments. He hates all of my friends and says he doesn't like them because they are all sl*gs. Which of course isn't true. He accuses me of flirting with his friends and says that I have slept with them in the past. Which again is not true. I feel like I'm walking on eggshells with him just waiting for him to find a problem with something else I do. He hates when I put a photo of myself on social media. He states that I only do this because I love attention from other men. I have recently started a new job and a few male colleagues have requested to be my friend on Facebook. I didn't see a problem in this as they are all either married or with a partner and have in no way tried to hit on me. He flew off the handle at this and said this was my way of accepting other men's advances which of course was not the case. He said because I had done that he has started to add single girls onto his Facebook and messaging them. Over the past few months his behaviour has worsened he's become violent. He kicks and hits me, he has dragged me around the streets by my hair calling me a dirty wh*re. He said it's my fault that he is violent towards me because I provoke him. I slapped him back once in self defence, which may I add I am not proud of as I am in no way violent, but he wrote status' on Facebook saying that he was sick of being attacked by me and asking other girls to punch me and rip my hair out. He constantly calls me awful names such as a fat ugly sl*t and says I'm easy and have been with  loads of men. He also takes my phone from me and reads through all my messages. Reading this back I feel like I've been a mug for sticking with him for so long. And if I was on the outside looking in would be giving me a good shake and telling me to sort my head out. Why did I stay with him? Well he has a lovely side too however it's like he has a switch that turns him into a monster. A real case of Jekyll and Hyde. We had some really good times, but unfortunately the bad is definitely outweighing them now. Worst of all he constantly twists the truth. Retelling stories differently to how they actually happened then calling me a liar when I state the truth. I feel like I'm cracking up and some days I really do feel like it's my fault. He has a severe victim mentality and feels like the world owes him. He often threatens suicide when I try to leave him. I've had to drag him away from bridges at 2am and require police involvement when he goes missing for hours. I've supported him finically for the majority of our relationship. He hasn't had a proper stable job for over a year now. He is 30 and I'm 22, he says I'm too young and immature. However I would say the immaturity is on his side. He blames me for ruining this relationship, says that he is leaving because I won't accept what I've done and makes sure that he tells others 'what I have done'. I feel lost, hurt and a little betrayed that I could give someone my love, trust and utmost respect yet he still states 'I'm the worst girlfriend he's had because I'm nothing but a mental bully'.