I am 1 month pregnant and am apprehensive about my marriage. Please help?

My husband used to be short tempered. Married for 3 years. When angry he yelled at me unnecessarily, called me names,made me cry,go nuts. Blamed my parents for everything they did. He wouldn't do any work watsoever at home although I work full time just like him. He also leaves his shoes , socks and jackets all around and NEVER puts them in their place. I would do all the work and he couldn't even do basics. He had started smoking since 2 years and has been telling me forever that he'll quit over the weekend, but hasn't. He insulted me by yelling and admonishing me in front of my parents on my birthday when they visited 4 months back and was kiddish and immature and moody. Even since then I've felt like I cant take it anymore/that I might not want to live with him. Told myself that I'll give it 6 mths. It's been 4 mths. he's chnged a little, been lovin. still smokes. I was very excited abt the pregnancy. After a wk I'm worried that having the baby will oblige me to stay with him foreve