Hi erica,
I agree with what least and the others said. The first thing that you should do - and the only thing you have control over - is to get yourself sober. These other issues will only continue to snowball and get worse if the drinking continues.
That being said, you need to be in as positive an environment as possible while getting sober. Living with 2 people who drink, 1 of whom has alcohol issues himself, is probably not the best idea.
You can't MAKE your boyfriend understand your addiction (and he might not want to acknowledge it because it hits just a little too close for him... he could very well see a lot of himself in your behavior), and you most certainly can't MAKE him support you, or quit drinking himself. What you CAN do is help yourself. Focus on YOU and your recovery. And he will need to do the same - he will need to focus on himself and learning how your recovery will impact his life. And it WILL impact his life if the two of you are going to be married. If he can't or won't make the necessary changes to help you keep yourself healthy, then maybe it's a good thing it's coming to light before the wedding. There is no rule that says he has to quit drinking just because you do, but there are certain courtesies he should give you, like not drinking in front of you (not keeping any alcohol in the house is even better), and not arguing with you about whether or not you have a problem. If you say you have a problem, then you do - whether he thinks so or not. He doesn't have to agree, he just has to accept it. Al-Anon can help him with that.
Good luck, and try to stay strong and stay focused on yourself. You can't take on the world, honey.