I would try to remain approachable, so when or if he desires to truly get help, he doesn't think he will get a "I told you so" response from you.
I would let him know you love him and that you will always be there for him.
He's obviously struggling badly.
“All modern American literature comes from one book by Mark Twain called Huckleberry Finn. American writing comes from that. There was nothing before. There has been nothing as good since.” - Ernest Hemingway, Green Hills of Africa