Well, first, let's address the wee issue. If he smoked weed during the four years you were dating him, then you either made your peace with it, or you didn't mention that you disagreed with it. You had four years to decide that. If he just started smoking weed after you married him, then you need to tell him you have a problem. That said, two years is a long time to put up with "bad" behavior, before bringing a baby into the world. Did you ever talk about these issues before you became pregnant?
A baby is very stressful on relationships, even when things are going great. If things have not been going well, a baby only adds more stress. He's probably hiding from his problems and smoking more weed as a form of escape.
The fact that you've been gone two weeks, and you haven't bothered to contact him indicates you share as much disrespect for him as he does ambivalence toward you. The two of you probably should have bothered to get married if you didn't like each other. As for the child, well, I'm sorry for her.
Have you realized that he's not the one? It doesn't matter what he's decided. What do YOU want? If he wants you, you'll stay, I'm guessing. If he doesn't want you, you'll likely cry and beg him to take you back. But take a deep breath. What do you actually want? If you want a real marriage, then you need to decide that and then act like it. Communicate with your man, openly and honestly.