Quoting Will☮Creedence:" I think you need to tell her to stay away, and I'd be pissed at DH for just letting smurf slide too."
Be pissed at him for what? That's her friend. She should have been the one to speak up. I wouldn't even put my husband in that mess. She specifically said "won't talk to her FOR ME
" Why should he talk for her as if she's not an adult?
Edit: I didn't see her post saying she started out being his friend. In that case he should say something but its probably not bothering him like it is the mom. So OP you should take the lead on this because it's offending you. I would only get mad if he contradicted me to her or made it seem like less of a deal than it is.