My take: (Jennifer) Brook wasn't the villain after all
1. Manual failed to end his relationship properly, and he ended up hitting the voo-doo woman after she hit him. Based on what I translated from the argument, Manual likely cheated on the voo-doo woman.
2. Jack wanted to confront, possibly fight, Manual after he hit he voo-doo woman. Jennifer had to stop him from doing that.
3. Manual had an attitude against rich people from the very beginning. He was employed to serve the customers, and Jack wasn't being unreasonable with his requests.
4. In anger, Manual caused the boat to burn. It was an accident, but his actions still led to the burning.
5. Manual saved Jennifer. She knew that she could not survive without him. She also knew he was flirting with her. She tried to disuade him from lusting after her because she knew it would cause problems, but he continued. So, what could she do?
6. Manaul and Jennifer saved Jack, and Jennifer remained loyal to her husband, nursing him back to health. In return, he only continued his beef with Manual, making their survival all the more difficult.
7. Jennifer was starving, and Jack's attitude prevented her from seeking food from Manual. She had to sneak food from him, only to have him bribe her with sexual favors in exchange for food. She couldn't rely on the jealous Jack, and she couldn't rely on the horny Manual.
8. Jennifer constantly had to save both Jack and Manual from killing each other.
9. Manual raped Jennifer. Yes, it was a rape. As he started, she knew she had to let him have his way. What else could she do? He was going to have have sex with her regardless, and if she would have fought him, he would have beaten her, and possibly killed her. In addition, he had the food, so if she kept refusing him, she would likely starve to death. Also, if he would have bruised her up, Jack would have went after him, fighting to the death. So, she had to allow the rape to occur, and then play along with it.
10. Post rape; I think everything changed for Jennifer. She was traumatized, violated, and the threat against her survival was certain. She couldn't survive living between the two men, so she had to start thinking of her. It was no longer her role to protect either man, but to do what she had to do to survive.
Anything thing that happened after that could be excused, since Jennifer was on survival-mode. She had to go there because the men she relied on where both violent and unreliable. As such, I don't blame Jennifer for doing what she did. She tried the best she could initially, but it was the men that ruined things.