My daughter and me. How do I deal with this?

She is 24 dating a complete idiot for the last 5 years. I have watched her support him financially half of that time because he is too lazy to get a job. He barely got his GED yet she is *** laude after getting her BA. He has been a crack dealer and when the house was broke into my daughter was hit on the head with a gun which resulted in 18 staples. I have spent countless hours listening to her complain about him and have heard how he trashes her things and has affairs. She has lied to me....I told her I would not pay for anything if he was living there while she was in college...and he was all along. And I paid all along. I have had words with him about his behavior and he has called me every name in the book. I haven't allowed him in my home for three years. Last weekend they broke up, he went to jail for the stupid things he was doing,.,and she swore up and down she was done with him. That night I get a call that scared me at 1 am. All I could hear was someone saying get your hands off me...sounded like the phone dropped and there was a scuffle. I jumped out of bed and ran to her house!!! It was not her,,,,,but at that moment....I begged her to be done with him. I can't handle the pain and pressure of wondering if he will kill her eventually. Today I find out that she is back with him. She says she loves him. I'm heartbroke and angry and can't even look at her. Any ideas on how to handle this?