So sorry you're hurting... I've been there as well. Only now my in laws have moved to hating me territory and hurting my kids to try and (I guess?) bully me into taking AH back? I don't know their thinking but I know that AH obviously came from sickness and his parents have shown their true colors and how ill they are since he moved out. Like your in laws mine were seemingly supportive through rehab and seemed to want AH to get well, but once he was asked to move out (and arrests and RO's followed) they have enabled to the heavens and mounted a hate campaign against me.
Sadly, even though they are my kids grandparents, I have now been forced to go NC with them for my well being and my kids.
I am sorry you are headed down a similar path and I hope that your inlaws won't destroy their r/s with their grandkids but if it comes to that don't hesitate to protect your kids and cut them off...