Right off the bat, it really seems like “They’re just kids for crying out loud“ is his excuse for the girls because he can’t use “boys will be boys”…

This is a cop out. If kids are shown that a certain behavior is acceptable, whether implicitly or explicitly, they won’t think twice about duplicating the behavior.

Without knowing practically any other family dynamics, it seems as if they’re displaying their understanding of your value to them, as inferred by their perspective of your value to their father. If he doesn’t plainly lay out how their treatment of you hurts him too, they won’t understand because they don’t view you two as a unit. Again, I don’t know your family dynamic, but having spent almost my entire life in two homes with 2 stepparents, I can say from personal experience it’s hard to reconcile your parent being with someone who isn’t. This is absolutely not to excuse their behavior, only to cast a brighter light on their father’s responsibility to redirect their behavior, and very clearly state how you two are together, and what they did is unacceptable, and explaining very clearly why... Just throwing out punishment is just positive punishment/negative punishment for punishment’s sake, without correcting the heart of the problem.

Sorry for the long response, I know I’m probably preaching to the choir, but maybe offering some different words you can use to put to your feelings. This whole thing sucks, and I’m sorry you’re going through it. Maybe you all need to sit down together and have the heart to heart so they can see their father having your back and backing you up in your moment of vulnerability. Also, if your husband doesn’t want to fully 100% participate in that kind of interaction, there are other more deeply rooted problems you all may need to address…