(((Sister)))
The way I look at it, there are two choices:
Get involved or step back.
If I had to be completely honest, I'm not sure where I would stand...so I understand.
Perhaps you can call the rehab and ask these questions, get the "real" scoop and set your mind at ease. Ask the med questions, ask about his safety, ask anything you "need" to.
As hard as it is, it seems the no contact with him might be the best plan.
NO need to ask for us to bear with you...we're walking with you, and I know how difficult this is.
(((Hugs)))