Misslissa, I have been on both sides of the position you are now in. I am 53yrs old and have been clean since 1999. I've been married 3 times, (twice during my addiction), and all my wives were, (and 2 still are), addicts. Most, if not all, of my friends and girl friends are addicts, (keep in mind that when I say addicted I'm not only referring to drugs but to alcohol as well. It is not only a drug, but by far the most damaging, life costing, drug there has ever been).
I'm telling you all this because I can't make it more clear that I have enough experience on the subject and its sub-categories like relationships, to tell you that I have never seen relationship of any kind work when one person is abstinent and the other uses. It makes no difference if he's putting cocaine in his joint or if he's snorting it directly because the point is whatever he's told you that he's doing, he is actually doing a hell of a lot more than that. Anyone who has enough cocaine to waste it by sprinkling it on a marijuana cigarette is most certainly snorting it or smoking it in a number of different and far more effective ways.
I guess what I'm saying is that you just will not believe, nor are you prepared for, the kind of living hell you are about to go through for the next 15 to 20 years if you don't break it off with him NOW and get away while you can! I don't have enough time to go into it, but you need to know that I'm telling you this not from some personal belief or opinion that taking drugs is wrong. I'm telling you this as one very psychologically battered person/recovering drug addict, to simply help another human being. Whether or not taking drugs is good or bad has nothing to do with my answer here.
Don't try to help him, or fix him, or understand him, or anything else you make think you can do for him. You cannot help him because only he can do that. And he's not even thinking about it and won't until he has fallen and hit the bottom of the Bottom. But you'd better believe me when I tell you that he isn't going down there alone if he can help it. He will take you or anyone who's foolish and naive enough to stay with him.
Sorry if this is not what you were hoping to hear, (and I'm sure that it's not), but you'll maybe one day, see him again and he has taken the ride that we addicts all do, and he came out wiser and very much sober.