This is a terrible place to be.
Right now, all I can say is let her know you are there (which you do) when she is ready to take a look at the relationship from a distance (would she go on a "girl's weekend" now and then? out once a week?). Also, given a chance put the local women's shelter phone number and abuse hotline into her phone.
If you haven't, let her parents know you are there and you care.
Send her texts/cards/invites/ And do be real with her. If he dies tomorrow she will not, she will not die if she leaves him. She might if she stays. Let her know that you understand it won't be easy for her to leave and regain her self esteem but there are people who can help with that---people who have been there and are feeling much better now...