Most everyone thinks their case is different. The casual drug user never believes he/she will truly become a full blown addict, the casual drinker never thinks he/she will be come a full blown alcoholic. They think those people live on the street or under a bridge somewhere. Spouses of addicts/alcoholics never believe their spouse would ever physically or emotionally abuse them. Everyone thinks they can control the situation. That attitude is called "terminal uniqueness" and it will kill you.
Like someone else said, this is my last post on this thread. If 70 posts from people JUST LIKE YOU don't convince you to slow this train down, then nothing else we can say will. You think you have control of some things, but you do not. You may think that he'll straighten out once you get married. He will not. The only difference is that you will be legally attached to him and his troubles will be your troubles and his disease will become your disease.
Again, I sincerely hope that you will read and read again all these posts from people who know what they are talking about. You came here asking for our help and we have all given it freely. We have absolutely no reason to lie to you and we are not mistaken when we tell you what is most likely in store for your life if you marry this man. I wish all good things for you.