Please help!!

My younger sister is in trouble, and I feel she is not listening to my advice. I found out yesterday that her fiancee has been verbally abusing her and has even threatened to hit her. She said on Friday he wanted her out of bed so he pulled her out by her ankles! He is always buying her extravagant gifts and then holds them over her head. I have never liked him, but kept my mouth shut. But after hearing this I told her it's time to leave. She's hesitant because She is a full time college student and can't afford to live on her own and doesn't want to move back home. I've told her verbal abuse often turns to physical especially when he's already threatened her. I'm scared because she told me stuff and it sounds like he is already trying to isolate her from her family. She left and is staying at my mom's house after he verbally assaulted her abiut not bringing him food. She said she hasn't made a decision yet. Any advice for me or her in this situation?