This is the kind of adventure that they will remember, fondly, when they are 40yrs. old!!!!!!!!!!!!!
AGREED. My DS14 is really close with my parents, and they play cards together several days a week. It's SO important for kids to have that connection with extended family.
Don't let this guy make you feel bad for filling your kids' lives up with healthy people.
It's his misery, and it's in his control to change it.