I don't have any advice, just wanted to say I used to be your wife and my son is your son. Weed and then a whole of other things, addicted to world of warcraft to the point of playing until 4 every morning, unable to hold a job. Doing nothing but being holed up in his room day after day. I was always as worried about WOW as about the drugs, because my son was unable to participate in life because he was caught up in a make believe world.
I enabled my son for many years, employed him, helped him out, gave him a place to stay. The result was that he just spiralled deeper and deeper into all his addictions as he didn't have to take responsibility for his actions, I was always there as his safety net.
Friends tried to show me what I was doing, but I just avoided them. I had to get to the point where I had enough to take action. In total it took me 10 years. I woke up one day and knew I could do it no longer and my son left that very day. It was also the time I found SR and it was good to understand that the point I reached was reached by many other people and I didn't have to feel guilty.
You are in a tough situation and I don't know how long it will take your wife to realise that she is as unhealthy as your son at the moment. Would she be prepared to go to NA or join SR?