Well doggone it...
There are so many wise parents here who have walked this walk, and many have already posted. Getting out of the way so his HP can help him is a good plan, so is taking your own stuff one day at a time so it doesn't get too big and hairy and scary. I've read so many stories from As and their parents that it took more than once to get it right, but that taste of a sober lifestyle doesn't go away... and it DOES get in the way of their next research trip. Hopefully he'll remember what it was like to be clean and sober and will want to get back to that lifestyle soon.
Hugs- I know it's not easy. Take good care of yourself, too.
Cats