My advice is to read the "Sticky" treads at the top of the forum and whatever you can about alcoholism. Also do a search on this board for a post on "red flags".
As a mom to a girl about your age and I'm married to a guy who sounds like he could be related to your boyfriend if you really want advice. Read all the posts on here. Really hear what we are saying and run. So much of what your saying is already what we would call "red flags". Like "he's nice when he's not drinking" the "two DUIs" umm "his family has alcohol issues" and you sometimes feel "crazy". All things we here go through. I'm sure you get other posts from people farther along in recover who can explain all this in greater detail better then I can.
But let me say this. Alcohol is alway progressive and you guys are young. This could just be the beginning for you of a long downward spiral. Also if you keep reading the posts, the longer you stay the harder it is to leave. I'm not sure why that is, but many of us here end up "trapped" unable to leave even though we could. I'm sure it has something to do with that "crazy" making they do.
You don't have to take my word for it; just keep reading. Just from what you've written so far I think lots of things on this site will really help. At least they did me and I came here feeling a lot like you...