Oh man Jim, so sorry to hear that. As far as blocking him from hanging out with those particular friends, I'm just going to share a story of what my brother is going through this week:
His daughter got in with "the wrong crowd" and started drinking heavily and doing drugs. My brother and his XW were both of the mind that "if she's going to do that I would rather her do it at home so I know where she is" and welcomed her shitty friends into their respective homes. She started failing classes, skipping school, couldn't hold a job, etc. But hey, at least they knew where she was! (rolling eyes) So she finally decided to wise up and try to get into the Navy where she would be FORCED to have some discipline in her life. She tried out and was accepted and stayed clean through boot camp and got her station assignment. I think it was in Chicago? My brother is here in TX. Anyway she got her first leave recently and went home to visit and guess what? She had a nice little drinking and drugs party with her old friends RIGHT IN MY BROTHER'S HOUSE. And yes, basically with his permission although he pretends to not know drinking and drugs were involved (ummm, what did you think they were doing, playing Monopoly?) Anyway long story short, he called me a few days ago and said she failed a drug test and got kicked out. So where does that leave her? Who the hell knows.
My point being- take this thing with your son very seriously even if your W doesn't. Bring the hammer down on his hanging out with those friends. Be loving, but very clear and firm. Draw boundaries and give him the consequences of breaching them. Stick to your guns. Hopefully you get buy-in from your W, but if not then you've got to be the discipline.
