Well, you can force him to do one thing: leave your home if he doesn't comply immediately. That's called setting a boundary. Now, here's the hard part: you must be willing to follow through with your threat if he fails to secure a job, submit to drug testing, and enter a rehab program. If you're not willing to do that, then things will just continue at status quo.
Have you and your wife attended any Alanon meetings? They will be quite helpful to you. I'm sorry for your pain and good luck.