My experience has been that "hands off" is the best policy.
The more I tried to help my son, the worse he got. And then he blamed ME for relapsing!
I needed to let him find his own way, as Pebbles said, and experience the consequences of his behavior, while letting him know I will always love him. This was not easy! He nearly died twice.
Today he is sober since he is on probation & also has just inherited his father's money. His dad, my ex, just passed away last week from his addictions. Right now my son has reasons to stay sober, but once those are no longer there....
All I can do is be a living example of sobriety and a loving mom. He knows where to go for help and that it works. The rest is up to him.