Obsessive relationships

Ok so I just got out of a weird relationship. Moved way too fast was engaged and talking about babies within 6 months kinda fast. Anyway this guy has had issues with drugs and alcohol for the past 6 years. Got clean but would relapse everyone so often.

Now about the relationship. When it was good it was really good but when we would fight it'd be horrible. Different fighting styles. I like to be given space while fighting and he was the total opposite. Was up on my sack more and made me more mad. Didn't give me time to calm down or anything. The next issue is one night he got drunk (I didnt know this till way later) came to my house picked me up and all he did was call me a bitch...took me to the middle of no where and socked me in the face. To the point he busted my ear drum and left me with a swollen face. I told him the relationship was over. But he couldn't take no for an answer. Would constantly threaten me about taking his own life, my life, family etc. What I wanna know is why do guys get like that?? Also if he finds another relationship will he be the same way with her? I'm just so confused heart broken and scared. I find this man to be dangerous. Mainly needed to vent. Thank goodness for this app