It's what I do for a living. Contact the Department of Human Services, in most states the State will assume the role of prosecutor if the woman will file a complaint. Keep reaching out to her. Many of the folks I work with stay in the relationship - but I work hard at empowering them with a "lock the abuser up" and they'll stop mode. Usually the abuser does stop after getting busted once. Stay with her and keep reaching is the only thing I can tell you.