how do I help my friend..

My friend is in a bad abusive relationship. Long story short she cut me (her BESTfriend) off and several other of our friends. She cut everyone out. We ignored it because we were done with her coming in and out of our lives and last month we found out why. A couple weekends ago  she came over and opened up about everything, she wants to leave this guy. She's not happy. She was talking about how he hits her, emotionally abuses her, it's awful. She said that she was going to just end things. I knew it wasn't gonna be easy and she wouldn't be able to just end it with the snap of a finger but he lives with her and she's constantly around him. He's may be getting arrested for armed robbery, but they're building the case still and she said she wants to be there for him to "keep his spirits up". She was supposed to come to my house Friday, no show. She's been lying to me and our other bestfriend. She lied to her mom last night and said she was with me. I haven't seen her in 2 weeks. She's ignoring me but I know she's with him. I'm worried sick about her. She's dropped out of college for him, lost her job, and given up her passion for dance.. I have no clue how to help her...