I know how hard it is to tell your son he can not come home. We had to put our son out of the house almost two years ago. It was one of the hardest things we did but for the first time my husband and I felt like we were finally doing the right thing. He is now 24 and still having a very hard time staying clean. He graduated H.S. and dropped out of College due to drinking/drugging and now it is almost 6 years later and he can barely keep a job due to continual relapses. He's been in and out of numerous rehabs and SLC's.
All of this is so very heartbreaking, tiring and frustrating!!!
I think you are very realistic in foreseeing what may happen if you allow your son to come home. I know our son became complacent each time he had a roof over his head. There were a couple of times where he seemed truly genuine but each time he cycled down hill and would be right back to drugging.
When I look at the amount of self sabotaging our son has put himself through it takes my breath away.
There are no easy answers!!
Have you and your husband considered helping your son go to a sober living community. He will be required to go to meetings during the week, find a job and contribute.
Wishing you the best!