It sounds pretty bad. Do you have a back-up plan, a place you could go if worst came to worst?
My only advice is to talk to him and be totally open about how you feel, try not to be accusatory though. I understand it must be hard to trust him but if you accuse him he'll only become defensive and not want to talk or make changes and it could get worse. Try seeing a marital counselor as well. Best wishes!
I am so sorry to hear about this. It's unfortunate that you're going through such a tough time with your husband. I do believe most married couples will have a moment (if not more than one) in their marriage where both participants are not on the same page and that causes major conflict. Are you currently pregnant? I honestly don't have any advice for you because at the end of the day, you have to make the decisions as to what you want to do. What I can tell you is to be patient, honest, and definitely communicate with him. Right now he is not giving you any reason to trust him, especially when he's hanging around people who abuses drugs, but I think the more you ride his back the more he'll possibly push you away. In the mean time when he's hanging out with friends and not spending anytime with you, do things to make you better and spend time keeping busy so you're not always thinking about him. Clean house, read books, exercise, hang out with friends and family... Again, I don't have the answers but what I can say is stay strong. Hopefully he'll come back around. Marriage is for better and worse and unfortunately you're going through one of those times... Good luck and God bless!