What rights do I have if my Husband is slowly abandoning our kids and I?

I have been married for 18 years. My Husband and I have two children, ages 17 & 14. Our 17-year old is pregnant, due on 3/30/13. My Husband has always been the main Bread Winner. Although I have worked part time jobs, on and off through the years. Our agreement was for me to stay home with the kids since he makes enough money to support us. Almost 3 weeks ago, he decided to stop coming home after work. When he finally does come home, he's drunk, doesn't say a word, goes to bed and locks the bedroom door. We have one working vehicle, his truck and my car (in his name}, which has been sitting for one and a half years. He refuses to get it fixed {needs breaks and battery}. I have no money, no car, and no family. I am trapped. He has always been verbally abusive, as well as extremely controlling but now he barely speaks a word to the kids or me. I want out but don't know where to start. He is barely providing food for us at this point. I don't have any money for a Lawyer and no car for a job or to bring my kids where they need to go. I'm terrified. He has supported me for 18 years and now he's leaving me with nothing & nowhere to turn. Any advice would be very much appreciated.