When I found out and confronted him (more than 30 years ago), he quit. I went thru the emotions you mentioned, prayed, read about it, went to Nar-anon meetings, and told his parents (no-one else other than a therapist – I still haven’t talked about it with anybody, but him). I figured that if he was my child and he was trying to kill himself – I would want to know. I stayed out of his way and tried to have the best day that I could, everyday.
