Your son is making clear to you that HE DOES NOT WANT TO BE IN THE MIDDLE. Your son and his wife are trying to make it work with two sets of in laws. He seems to go nuts when you complain or criticize this family.
I would try the best I can NOT to go there with him. You risk alienating your daughter in law and maybe even your son. I would really, really try to keep my mouth shut no matter how bizarrely they act. You will be the loser, I fear.
You have no control what so ever about the behavior of these people. And your son will blame you if you continue to make it an issue. He has made this clear. It could be affecting his relationship with his wife.
While I commiserate with you very much, if such a thing happens again I would stay silent.
