From one mom to another: Kids do this, even the ones raised with the best of parents.
It's NOT YOUR FAULT. Good parents are up against a bad environment; people and enterprises who have their own motives for undermining parental responsibilities and authority. Emotion aside, what are the odds that the child will stick with the parent through thick and thin? The very best children (and mine were the very best, good hearts, good motives) can be turned aside just because there are more of "them" than "us"; our voices get drowned out in the cacaphony. Sometimes it happens while they are very young, other times after they are grown, but it happens...it doesn't mean you've failed.
Do not lose heart. This is temporary. Your son will be thinking, observing, and remembering, even though you won't see any signs. The worst thing you can do right now is to cower down, to buy into the notion that you did something wrong. Sure you made mistakes, every parent does! Whatever those mistakes may have been, it doesn't matter and you don't owe anyone, even your child, an apology. Everything you did was done out of love and in the best interests of the child *as you understood things at the time*. We learn as we live, and maybe you would have done some things differently if they had come up at a different stage of your life, but that doesn't make you "wrong". You handled life as you understood it at the time, and there's nothing reprehensible in that.
You will grieve, probably for a long time (as in years). This isn't a situation that will resolve quickly. Take it from one who knows...and believe me when I tell you there's no way you'll come out the loser on this. The parent-child bond is one of the strongest things there is. No matter what outside force tries to break it, it will remain intact. Grieve, because you are going through a period of deprivation, because your concern for your child seems like it can't penetrate the "wall", but at the same time, remember....he's YOUR son. You're his mom. That bond is still there, underneath, while your child is "unconscious" (not-conscious) of its strength. He'll say and do things that you never could have anticipated, but that's because he is caught in a malestrom only partly of his own making. Ride it out, never give up on him. He's thrashing around like he's delirious (he is), but he will come out of it. You wouldn't take offense, or try to reason with, or punish, someone for what they do when they're delirious, would you? Take that same attitude toward whatever he does now; bear the anguish, and fight to remember that it's not "him" that's doing these things, that something external to his own thoughts and heart is affecting him.
Little by little you will get your son back. Hold on. Give it all the energy you would have given if something had happened to him as a child. Put on a brave face for the world (defend him when people denigrate him) then cry your heart out in the privacy of your home. Whether you can "see" it or not, there are people who know you didn't do anything wrong. There are also people who have been through this very thing, had their own seasons of despair, who are now seeing things turn toward the good. Once that happens you won't remember how bad it was, you'll only feel gratitude and relief for having your son back.
It's going to be rough for a long time but he WILL return to you. Let that reality hold you steady through this time of turmoil.
From one mom to another with love and tears,
AB