WOW is the pain what exactly? None of this is your fault. It sounds like you projected to him a love of Hashem, Yiddishkeit etc.
He got involved with people who showed him an ‘exciting ‘ life and there was nothing to fill that void in the community. Perhaps you can learn to accept him as he is. If you can’t remove him from the home that is. If in fact drugs are involved then you need to get him into a rehab and recovey facility.
It would depend on which drug but unless it is ‘only ‘ marijuana that is anything harder is a absolute danger to his life.
I am speaking as knowing a young person from a frum community who over doesed and halach liolamo.
So if this were me, I wouldn’t have so many illsions about that aspect of this. You seemed to be unable to deal with that part.
But you haave to determine. also alchohol if drunk too much of is toxic and kills. that is people do die from drinking too much.