I think the best thing you could do for her right now is maybe try to be a friend.... I know you hardly know her but perhaps send a little invitation to have her come over for some tea or something. Other than that what can you do. the police have been called and he seems to have left. But trying to establish a friendship might give her someone to open up to in case she doesn't have anyone else. or maybe drop by sometime and invite her out for a walk with the kids.

But at the same time you don't want to put your family at risk from this horrible man.