Just personally,
I would not touch this socially with a ten foot pole, if the relationship is over with her mother it is very likely any communication with her will be taken in a very wrong way. Avoid at all cost, if you have known her for a while then maybe you can have some kind of relationship with her as an adult. Still regardless of how long you have known her, her loyalty is going to be with her mother. Anything you say to her will probably be twisted into what "that man" said.
Sad but probably true,
That is my opinion anyway, I am not great at social situations but I would say as little as I could to her.