Dear Rebelson,
I have been reading along but too busy to post. I am sorry about your latest worries with your son. It does not sound all bad and it sounds like others have given you good advice.
I agree with SWOT about invading his privacy. I believe it could backfire. The only way he will learn is with the freedom to make his own decisions without pressure. I over-controlled my son and still fall back onto it sometimes. It did not work at all and made me sick. It boomeranged.
My son would not do what I wanted--and when I pushed too hard he pulled back even farther. Some of you will remember the fiasco of going to the big city to make sure he got to the liver doctor. If I was not shameless, it would have been my perp walk. But the bottom line is it does not work. You will drive yourself nuts, and it does not help them.
My son is doing many of the things I wanted--because I am leaving it up to him.
As far as privacy goes, you want him to have boundaries and to feel he can make them. Those are attributes that will help him deal with addiction.
Take care.