My good friend abuses his girlfriend...?

I was friends with "Dana and Chuck" for about 7 years. Saw them fall in love, marry, have three children and divorce. It turns out that Dana's time in the foster care system had done a number on her. It slowly dawned on Chuck (and slower on me) that she was an adulterous chameleon. She cheated MANY times with ANYONE, had a child outside of their marriage, lied daily, taught her children to lie, and would basically blend in with ANYONE she was around no matter how she felt about them. She was a mess. Chuck and I were shocked to realize that we didn't know her at all because she has an amazing ability to behave in any way that is conducive to getting what she wants. After they split, she had a parade of boyfriends she referred to as "daddy" when speaking to the kids, continued to lie about numerous things, had some legal problems, neglected the children, and put them in dangerous situations. It was all very difficult to watch- even as a friend. Eventually, I had to stop spending time with Dana, but continued my friendship with Chuck.

Chuck has custody of the youngest child- the only one who is biologically his. He's a sensitive, artistic, funny, and intelligent man who is from an alcoholic and abusive home. He has a new girlfriend, "Sadie." Sadie is a good woman with a good head on her shoulders. She really loves Chuck and his child. She's been a mother to his child for three years now. In the past 9 months, Chuck has beaten Sadie twice. Once, he forced her into the vehicle, took her into the country and kicked her repeatedly. He also threatened to drive off a bridge with her and used an awful lot of force to keep her in the vehicle. Another time, he's body slammed her and beat her. I've NEVER KNOWN him to be abusive and I've been good friends with him for 10 years now (7years with his wife, three years with Sadie.) Still, I'm not shocked hearing this today. He's still very angry at Dana, but doesn't deal with it. Instead, he just refuses to talk about her. In the heat of the moment, he told Sadie to leave, and when she packed her things, Chuck's child packed also, saying "I'm going with Mommy." Chuck threatened that if Sadie took the child, he'd have her charged with kidnapping. He promised both times to get help, but has sense refused and becomes very angry when it's brought up.

Sadie is stuck in between a rock and a hard place. The child already has abandonment issues because of Dana. Sadie has been a real mother to this child. A lawyer has told Sadie she has absolutely no parental rights. Sadie has no income and is a stay at home mother. Chuck has been isolating her lately, and she doesn't have much access to a car. She loves Chuck and doesn't want to hurt him, but she wants to leave. What is the best thing for her to do? What is the best thing for Chuck? If Sadie leaves and turns him in, the child will go to Dana- which is a really bad place for a child. Of course, an abusive home is a really bad place too. I told Sadie to organize an intervention for Chuck asking him to get help; naming consequences if he refuses, but offering support if he accepts. Other than that, I'm at a loss and so is Sadie. I love them all. I'm usually cut and dry about an abuser wanting the abused to leave and the abuser to suffer consequences, but this situation is sticky. Finally, I see the abuser as a real person who is actually good. I used to think that sounded ridiculous when others would say it, but I've known him for a third of my life and he IS good. Help.