Depression Treatment Care

I dont, but ive done some research, my fiance , he is always mad, hes always yelling and screaming hateful things at me, i dont want to just give up on him, weve been together for almost 2 yrs and we have a child together and im pregnant again. To him its like hes always mad because things just never seem to go right or his way, hes not seen a doctor but im trying to find a solution to help him. Hes slowly tearing our family apart, and it seems like everyone in his family is the exact same way, what explanations can explain this behavior and what can i do to help him change? please help, i dont know how much longer i can handle the things hes saying to me and my children, i love him but if this is something that cant be helped, i love him enough to let him go for my familys sake….