An addict active in his addiction is out of control and spews his anger at anyone within earshot because the alternative is to get angry with himself.
Don't take his threat lightly. I doubt he meant it, but I don't know your son so maybe take extra care for a while.
No matter how much we love them, no matter how much we do for them, it's never enough. And giving even more makes it worse.
The best thing I ever did was to let go, stop giving anything, and letting my son find his own way.
Hugs