At this point all you can do is pray. I am certain you instilled many excellent values in your son and I expect as his circumstances worsen and his so called friends trickle away he will return to your teachings. Of course, he may never say so, but he will find ways to use what he has learned. The school of hard knocks awakens most of our kids over time. Eventually others get tired of helping and see what we see in our kids.
Just keep praying, as will I, and know God never gives up on your son, or any of us, no matter how much we screw up. His love is perfect, ours is a very poor reflection of what we will get when we see Jesus in heaven.
hang in there,