It doesn't sound to me like they just talk about the weather! I can't imagine berating a guest for their childrearing choices over a Holiday meal.
Honey, whoever did that is plain rude. Just because they have a little money doesn't mean they understand basic etiquette. In my opinion, it's not even an issue of culture, but one of class. It is not appropriate to invite someone over and then make them uncomfortable. Period. You don't have to defend yourself or your choices.
But don't let his family cause problems between the two of you. None of us can control our family members.
For what it's worth, I believe from many things you have written that you are an awesome Mom.