hi cat-
i agree with suki, to not label him as an alcoholic. you can merely state that you are not comfortable with how much he drinks and that you do not wish to pursue the relationship.
i think you are doing the wise thing in stepping back. look at all the problems his drinking have already caused: broken relationship, DWI, broken ankle, living with his parents. add to that his penchant for gentlemen's clubs, well, it's looking like a lot of heartache for you in the future if you stick with him.
naive