I'm sure far more experienced folk than I will be along soon, but I just wanted to say welcome and offer a hug for what you have been going through.
My fiance's adult son is an alcoholic/addict and was kicked out of the house after he threatened to kill nearly every member of the family, he brought a dealer to the house, a crack pipe was found in his room, he wouldn't get a job.........
My only understanding is that everyone reaches their own limit. Sounds like you have reached yours. Keep reading and keep posting!
Hugs, HG