I found her, now what?

I finally found my sister, I filed a missing person report and the cop went to her residence shared with her dealer abuser boyfriend. She barely said anything as the cop put her on speaker phone but when he called back after, he said she looked somber and remorseful. He told me if we don't intervene she is probably going to harm herself or be killed by her boyfriend. I think she may have stockholm syndrome. I've tried calling but her boyfriend owns the only phone and he just puts me off. I asked him if he is keeping her from talking to me and he flipped me some crap, then I repeated the question and he got all nicey nice and "poured out his heart" about how much she misses me and loves me and feels so sad and bad cuz she doesnt have anything positive to say cuz lifes so hectic right now. He says he's trying to get her to call, but when I called, he wouldnt let me talk to her.I was hoping someone may have had a similar experience and have advice? Should I just drive 4 hours and try to get her to come home with me? The cop suggested my husband and I go get her.