I would talk to them directly about it. Tell her that if she was just excluding you and your husband, it would be one thing, but she's excluding your daughter--her own daughter's best friend. For the sake of the kids, then, I would ask her to explain what they have against you. Otherwise, they don't sound like the kind of people I'd want to be friends with.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher