Re: Domestic Violence
At the very least, I would make an effort to document things, especially if they continue. If possible take pictures; if not, at least make detailed notes of dates, times, what she says happened, and any injuries or other physical evidence that you observe. If she stops telling you, still make notes of any suspicious bruises or other injuries you see. That way if this continues and she does get up her courage to leave, there's documentation to use in pressing charges, taking out a restraining order, or whatever else needs to be done.
Is this the first time it's happened (as far as you know)? What was his response? Is he willing to get some sort of counseling? I don't have any direct experience with this sort of situation, but it seems to me like he needs to get help and seriously demonstrate repentance and/or she needs to get out of that situation until/unless being with him is safe. Why did she want to leave him to start with? If it's because this sort of thing has happened before, then she does need to get out for sure. There are shelters available for women in these circumstances, where their locations will be kept confidential. She should also talk to the police.
Give me one pure and holy passion
Give me one magnificent obsession
Give me one glorious ambition for my life:
To know and follow hard after You.