Abuse and Love

My friend/sister is in an abusive relationship. He's controlling and very verbally abusive. I have watched her change and become more beaten down with time. She's left him once, and then when his daughter was going through a crisis, she against her better judgement moved back in with him.
He learned from that mistake and talked her into selling her house to him. They used that money to buy more houses, renovate them and rent them out. He has 5 houses now. None in her name. He sold her car, it was too much to maintain.
I see what's happening. So does she. When it's too much to bear, she calls me and I go get her. He spends the next day bombarding her with phone calls until she gives in and comes back. After all, she has no car or house, where will she go? She can stay here, but that's beside the point.
He has taken everything from her both physically and mentally.
I will be so glad when she finally dumps him or will he kill her?
But to be on the safe side, I made her sign a piece of paper in case something happens to her, the police will be investigating him. We also gave her a microcassette recorder and are will be holding tapes to use as evidence.
I secretly wish he would get picked up for DUI (He's had 3) or as horrible as this sounds, I wish he would just die.
When things are going his way, he's very charismatic, charming and some would say personable.
When they are not, it's a constant fight. On days like that, when he pulls in the driveway she calls me and I put my phone on mute and listen. I have gotten in he van and driven to her house at 2 in the morning to pick her up while listening the entire drive (90 minutes) anticipating at any moment having to call 911.
We are counting the days down and tucking every spare dollar aside for her emergency exit fund.