Aw BFA it's sad to see you bumming like this.
There have been some great points made here.
Things that come to mind for me...

If you are working out some tough emotional things yourself, that are unrelated to the relationship, you are going to have a hard time giving your man any emotional support, and it is going to be painful for both of you.

You both are still so young. I know it may feel like a love that could stand the test of time, but realistically SO many things are going to happen in both of your lives as you mature and pursue your own goals. The chances of ending up happily together are pretty slim anyhow. I'm not saying it's impossible, but if you are ALREADY having these issues (and the drug one is going to be very tough to beat without a serious commitment by both of you), then aren't you concerned that you might be spending so much energy on fixing the relationship that you are neglecting other things, like personal growth?

To me that is the most important thing for a young person to understand- and by young, I mean like under 25 when you and your peers are pretty settled on a career path for the most part. You have to make the most effort to take care of YOURSELF at your age. Later in life you will eventually become really self sufficient in other ways, and that includes emotionally, and you will HAVE that extra energy to nurture someone you love, whether it is a boyfriend or husband or a child or another family member who needs support.

I started seeing a therapist regularly during the course of my last relationship, which was with someone who I at first had thought was 'the one'... we lived together for 2 years and during that time I realized that I was cheating myself badly by being with a man who still had a lot of growing up to do, and expected me on some level to either help him do it, or enable his immaturity.

My therapist never said to break up with him, but the more I talked to her and began to understand my own role [enabler] in the dysfunction of our relationship, the more I saw that it was making me into a total stress case and I needed some time away to think.. I got on my motorcycle and took off for 8 days to Ontario... I reminded myself how good it felt to be the master of my own destiny... every hard time we went through after that, I thought of the freedom I was missing, and it didn't take many months after that to say time to cut my losses. I don't see my shrink any more- I feel like she gave me the tools to deal with this sort of thing so much better. I feel like I gained YEARS of wisdom in only a few months.

What you and your man are going through is going to make both of you smarter people and teach you both what you want and need out of a partner. You will of course have to ask if your needs, and what you have to offer, are even compatible.

Be true to YOURSELF. I think you are intelligent and I also think you probably already know the answer, know what you have to do- and it's hard- be strong.