Maxwell might just be stupid enough [View all]
to believe, if she says Crumb the 1st wasn't involved and she gets her pardon, that they wouldn't still go after her to silence her permanently once she was released. It's like one crook believing if he just gives up all the money to his crooked accomplice that he'll walk away rather than be silenced.
But Maxwell is an example of how having wealth and an education doesn't mean you make wise choices in life. Because of her father she never really had to work a day in her life and could have continued on a life of leisure. But the idle rich can become drunk with their power, position, wealth etc. and they commit all sorts of horrible acts.
Her best opportunity for herself, once arrested, would have been to lay it all out there in public. Every bit of it. Then the prosecution could do what it wanted one way or another but she would no longer have been holding any secrets that would make her a target for someone to eliminate her. Bad choice. Sick, depraved, educated and wealthy and still so unwise.