Hopefulmom - I am glad he showed up and that for a night you got some relief.
I would recommend moving quickly on getting him out of the house. Remember plans you have tried before that have failed - don't fall prey to promises that won't be kept only to find your own self in the same situation.
Regarding his depression. Was he diagnosed by a psychiatrist for depression and was he regularly (every month) seeing one for treatment? mental issues and addiction go hand in hand. My RAH was treated for depression for 10 years when he was not clinically depressed rather was bi-polar. Doctors are quick to hand out anti depression medication especially those who have no business doing so (GP's and gynecologist's). Depression is a symptom of many psychological issues - and sometimes it is a trial and error to figure it out hence a monthly meeting with a psych who can monitor if there is improvement (or not which is just as indicative) and adjust medications accordingly.
My other suggestion would be to look into a different sort of program for your son. Here, and I am sure there are many, are some detox/rehab that are geared specifically toward youth. This program is a months long program and is a work style rehab - they farm, learn to build/constuction, take care of the barns and animals and receive intense counseling. Everything is merit based i.e. it could be two months before you hear from your son as he would have to earn the privilege to make a phone call. I know 2 people who put their children in this type of facility and both were successful. I guess 2 people isn't a lot to base looking into it but it could be something you feel might work. If you are curious send me a PM I can find out the name of it so you might be able to locate something similar near you.
Your son is at a tough age IMO - old enough to be considered a legal adult but so young not to have the life experience to understand what the hell he is doing to himself and others. I certainly don't blame you for the choice you made if he was 30 or 40 I would have another opinion.
And yes I have before wished that RAH would just die. Not while he was relapsing but previous to that when I lived with him for nearly a year as an undiagnosed bi polar. At times, I felt so hopeless and when I looked at him felt his issues were so insurmountable that death may be a better option rather than to go through life so tortured. I don't feel that way anymore.
Hope today is a good day and as always you are in my thoughts.