Welcome Puddinface.... (((Hugs)))
Both my kids are addicts, both attended rehab, but my daughter's path has been the toughest in some ways.
She was in and out of rehab for almost all of 2004 and the first part of 2005. She started when she was 17 and, like most using addicts, had the maturity of a 14 year.
At 20, a child is an adult and should be able to make his way in the world.
When I was told that my kid should be able to make her way in the world and behave like an adult, I bristled - she was SOOO young! But the ones who told me that were right.
I had taken on the responsibilities for my daughter, who I thought of as "disabled". In doing that, I kept her right where she was ... "disabled". I stole from her almost every opportunity to grow and mature by taking away the consequences for every poor choice she made.
Today I know better, so I do better.
But rehab, especially if he can stick it out for 6 months, is an excellent place for a young adult to learn about taking responsibility for his own actions. A good followup for both my kids when they came out of rehab, was an Oxford House (a sober living arrangement - you can put the term "oxford house" in any search engine). That kept my kids from coming home and slipping right back into being taken care of ... and kept me from slipping right back into the "caretaker" mode.
Alanon helped me very much while my kids were in rehab. I hope you can find some face to face meetings as soon as possible.
(((hugs)))