I feel for you and your nephew. Sometimes with an addict of any kind, they need to hit their rock bottom before they wake up and change their life. Maybe your nephew is close to that point. Hopefully he is. It wouldnt hurt for you to talk to him but as hard as it is you really cant enable an addict, they thrive off that. Does that make sence to you? Your nephew will be in my thoughts and prayers.

I want to add one more thing, he might be doing more than the weed, you ususally dont sprial that out of control over weed.