Boyfriend's Drinking Problem... What to Do

Warning, Long Post, mention of violence. I have already posted in the domestic violence group.

I've posted several times in the past about his behavior and tried talking to him about it but it seems to be getting worse.

We have been together for 7 years, our son will be 2 years old in August and I'm now 15 weeks pregnant with our second. My boyfriend, the Babies father lives with his parents and we only stay with him on the weekends. Lately we have been arguing because he feels like I'm not there enough and that he isn't sexually satisfied because I'm uncomfortable doing certain things. He has a drinking problem and acts like a complete stranger and his behavior scares me when he is around us while he drinks.

We argued throughout the weekend and the night before we came home everything seemed alright until he suddenly left without telling anyone in the middle of the night. He called to tell me that he was at a cemetery looking for the gravesite of one of his friends and asked if I would stay up until he got back because he was upset. He came back soon after and asked me to come help him clear off his bed so we could sleep.

When I went in the room to help he kept saying things to me like "Suck it up" and began arguing with me again. He pushed me back onto the bed and pinned my hands above my heard and got on my legs so I couldn't move and got in my face kissing me. When I got up he kept putting his hands up like I was going to try to fight him and pushing me towards the door. Later that night while my son's grandma was rocking him to sleep, so came in and slid against the door acting completely out of it. His mother asked if he was alright and noticed he was holding a fork and tried to take it so he wouldn't harm himself. When she got it away he got up and tried taking it back from her, acting like he was worried she was going to hurt him with it. I snapped at him to leave her alone while she's holding the Baby. He went back to the door to smoke a cigarette outside and pulled out a knife, and his mom yelled at him to put it away. This caused his dad to wake up and take the knife from him but for some reason he gave it back and so stabbed a hole through the wall and tried to fight his dad. I got up and took my son into the grandparents room and locked the door. After everything was done, so's mother asked if we would stay in her room for the night and was worried if we left the house to go home he would follow us. So she packed our stuff and got the carseat out of his car in case. When so came in the room to get us, I told him that we were sleeping in his parents room.

He kept trying to get me to come out and his mother told me she was worried he would hurt me if I did so I said I wasn't going to leave that room. He then began vomiting and tried to convince his parents that I was being dramatic and turning what happened around on me. He began saying that I don't let him discipline our son and that he would grow up to be soft and would get hurt in school and hurt himself and many other terrible things about me as well. He said that all I do is run when we have problems like this and that I'm a coward, using his parents for protection. He told me that he was going to leave the house and find another woman to have sex with and kept walking through their bedroom in and out for hours grabbing my feet and yelling, he pulled my hair and tried to pull me off the bed by my ankles to get me to come in another room to talk to him away from his parents.

The next day I came home with our son and tried talking to him. I feel like he needs to get help with his drinking but he won't And believes that he can do this on his own and says we can't talk about it because all it does is makes him want to drink more thinking about it. I told him that I can't keep doing this, pretending like nothing happened. And that I don't feel like me and our children are safe at his house and that we could still hangout and he can see our son but we will not be staying the nights there for a while until something changes about this issue. He says that all I do is run when we have problems like this and that he needs me for support and understands how I feel but if I choose to stay away then he may come to resent me because I won't be there for him while he goes through this. I want to be there to help and be supportive but I don't think I can do it how he needs me to and I can't feel like me and my Babies aren't safe around him when he's drinking.

It's so difficult to deal with because after these situations happen, the next day it's like he's himself again and he's the one I'm in Love with but then there's this monster that comes out and it's been happening more often when we're there and seems to be getting worse every time. I wish I knew what to do and how to make it any easier