krhea, Becuse he is not quite yet considered an adult, I would toy with the idea of calling the halfway house & talking to his counsler. He or she should be able to guide you in what to do. The counsler probably saw the relapse coming. This is a hard spot to be in because of his age. I do agree "hands off the adict" for an adult. Once he is 18 you will have no say in what he does. But since he's not, you might be able to request that he goes to a program. I know that someone doesn't get clean untill he or she is ready, but I also think each time they are in a program they pick up at least one thing that can help them when they are truly ready.
I hope you understand I don't mean for you to get sucked back up into his drama. I think you did well not giving him a ride back to the recovery house. Hopefully he's thinkin holly crap...now what?