Emphatic no. The reason is always the same: we do not love each other any more/our marriage is not working any more. Unless the kids aren't allowed to see Dad because there was some sort of abuse or substance abuse going on, there is nothing more to say.
While I think this is primarily an ethics issue, I think there are some etiquette issues here because it deals with relationships. From an etiquette standpoint, she is under no obligation to be anything but civil towards Dad as they divorce, work out custody, and make future parenting decisions as a divorced couple.
It would be incredibly rude, I think, to tell the daughters something without Dad's okay. He may be a bad husband, but he's still their dad. Additionally, blaming Dad for the divorce and making him out to be the bad guy isn't all that polite, either. It puts the daughters in an uncomfortable position. They don't need to feel like they have to take sides. They don't need to worry that if continuing to love their Dad means that they are betraying their mom.
No, no, no.