I know relationships aren't perfect but are they supposed to make you want to kill yourself?

My boyfriend and I have been dating for a little over a year now and its always been a rocky relationship. We have known each other for 3 years prior to getting together. I love this man more than anything, I know that for a fact. I do everything for him and that's my downfall. Yeah he does a lot for me but I do more for him than he could ever do for me. I gave him a roof to sleep under, I make sure he's fed, I've spent more than enough money financially for him so that he stays out of trouble. (he's been in jail 3 times since we got together for stupid things that are in his past) Between bail, court fines, and money on his books I could have bought myself a brand new car with all that money and he seems to just take me for granted. Lately we are telling and fighting more and more. Cussing at each other. And then he turns around and acts like nothings wrong but makes me out to be the bad guy. The only thing he's done that's "benefited" my life is get me pregnant and I'm pretty sure that's only to make sure I stay. I've gotten to the point where I'm at a loss for what to do. I cry myself to sleep at night. I sometimes can't even sleep. I avoid talking to people that used to be my friends. Everyone says I need to leave him but it's not that hard when you're scared of the outcome that may happen. If I even bring up taking a break he freaks out and says if I don't want to be with him then tell him and he'll go live on the streets and do drugs again because of me and he'll fight me for custody of our kid. Its so stressful especially being pregnant. I just don't know what to do anymore. I'm at my wits end..sorry for the blabbering. I just needed to finally get all this out.