No wedding. No wedding until he is sober for at the minimum one year. I would also suggest that you move out to protect your self financially and emotionally. You also need support of your own because living with an active addict can make us crazier than they are.
Also, please know that very few addicts can "do this on my own". I believe because they don't know HOW to live life without drugs. They haven't been living life drug free for so long that they just can't face up to what reality is.
Addiction is for life. It is not going to be gone when he stops using. It is always there and they can always relapse. My husband just relapsed at Thanksgiving after several years clean (xanax and opiate pain killers) and is working a program now but I don't know if he is still using because I left him.
I left him once before and I wish I had stayed gone. We've had some good times together and I do love him and always will but sometimes love just isn't enough.
Good luck.