You lot seriously need to start showing some tough love. If they won’t go rehab tell them there’s the door you just need to be stronger. I once used and I had been giving tough love changed my life
I don’t think he will stop on his own.pull him up each week for a drug test just change the days around. If he is saying it’s because he’s depressed could you try to take him to the doctors. At least that way you will know he wants help.