I don't know what to do.

I feel like my marriage is in shambles. I'm 12 weeks pregnant, and he acts like he doesn't care. He works nights, and will come home and head straight to his work shop and mess with his motorcycle. Then he'll drive it around town, before I even know he's made it home safely. He does that quite often.
He has alcohol problems, and something recently happened and he said he never even wanted to look at alcohol again. That went great for about a month. 
He hates talking. Communication with him is like pulling teeth. Until he just has enough and explodes at me. He told me I'm driving him crazy and he doesn't know what to do. So I suggested a separation for a while, but he said no. It's gotten so bad at some points that I just pack my stuff and leave. But I always come back. I've tried talking to him about our problems but he feels like it's nagging. I hate to admit it, but I'm not happy. I know I'm pregnant and my hormones are going crazy but I can't think of any other ways to get how I'm feeling across. If he's mad, then he'll just go work on motorcycles or go do whatever- usually drink. 
I'm just so over it.