My girlfriend was sexually abused by her father, and I'm having trouble accepting it. What do I do?

I'm going to try and keep this as short as possible. I have been dating a wonderful girl for 10 months now. We are both 22. We love each other very much and are hoping for a future together. We have a very healthy sex life, and usually have it pretty often. There came a point where we talked about our past and past partners. I was relieved to find out she only had sex maybe a dozen times total in her life before me with a couple past boyfriends. However, she told me a while back that she used to be sexually abused by her father. She claims it went on for years up until she was 19! As of now she lives at home with this man. I have never met him since he wants to never meet me. If she brings me up, he gets into a rage. He's a truck driver, so is rarely home. This gives me a lot of time to spend at her house. But lately he has been home for almost a month. I haven't been able to see her because he is keeping her away. I don't know what to do. I'm scared for this girl. He is with her almost all the time now, and who knows what is occurring in that house. I don't dare ask her about it because I fear her reaction. I feel so powerless. I want her away from him. And I honestly can't stop thinking about what he might be doing or what he's done to her in the past, and that makes me sick. Bad enough when I think about the guys she had been with but I have to worry about her father too! Any advice?