I have the same fears and concerns about my 20yo son. He has been home from rehab for a few weeks and has slipped once. We sat him down and talked to him again and I told him I was done with his crap, not him, but his crap. Since then he has been ok but I just keep waiting for the other shoe to drop and I think I will for a VERY LONG TIME. I guess it all goes back to trust. It takes a second to destroy it but forever to rebuild it. I don't have any answers but know that you aren't the only one who feels this way.