Welcome to SR Peebee.... we are glad you found us.
Im sooo sorry that your son is an addict, I know how helpeless it is to watch someone you love kill themselves.
I guess would start with is learning as much as you can about his addiction... knowledge is power and will help you not feel so hopeless. Remember the 3 Cs. You did not cause this, you can not control this and you can not cure this. That alone gave me breath room. He really is not doing this to you personally.... its a disease and its not your disease to fix.
What worked for me was theraphy, Al-anon, open AA/NA meetings, SR and reading everything I could.... I suggest "under the influence" to help understand the physical.
Stick around.... read the stickies at the top and vent/post all you want. I look forward to getting to know you.