Very strongly encourage him to go to counseling, but also into a program for the alcohol.
You cannot fix him, he has to want to begin the journey to recovery. I would suggest printing out a list of therapists in your area as well as a list of local 12 step programs for the alcohol abuse so that he can choose to start to deal with his issues. I discovered first hand that just the act of quiting drinking isn't enough, he has to deal with why he started drinking in the first place. He needs to learn how to cope with his problems as opposed to numbing himself out. And you need to be careful to not fix everything for him - be supportive by all means but don't think that you can make it all right for him.
For your sake, please consider waiting until he is well on his way in his recovery before you marry him or bring children into the picture.
This all can be worked through, but he is the one that has to have the want to work through all of it.
I'm so sorry that your going through this - none of it is fair.
Your in my thoughts,
God has a plan for me, I trust in God's plan.