I think it is good that Carol's daughter can talk to her about this. When you are inside a relationship you see the problems from a subjective basis, but someone else, even your Mum, has a more objective view and can see the big picture. Women, well most women I think, would expect their Mum to say what she thinks.
I certainly would say what I thought. In fact my basic inclination would be to send a posse of the men in the family after the bastard and sort him out. But I wouldn't. You can get arrested for that! Alas!
Anger management!!! Help needed.