bookpusher, This is an issue between him and his parents. Stay out of it. When he's had enough, he will either tell them in person or not answer them. Blood is thicker than water and no matter what you tell them, they are going to do what they think is best--check on their baby boy.
I know you are trying to shelter him a bit so that he can get through his crisis, but this is not a call you can make. Unfortunately, there comes a time when you have to drop the rope completely and allow God to intervene and he will if your inlaws get too pushy.
Sit quietly and allow him to do his work. Your inlaws will have to learn the hard way about mlc. You've done all you can to explain things to them, now step back and let them screw up their relationship w/their son all on their own. They'll get it eventually. They all do when we step back and try not to make excuses for their behavior.
Hang in there.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
