Kudos for you for saving one, but I'm just a little confused how you ended up paying $400 to keep her from the auction, if she is small and fine she would of been a lot cheaper in the ring.
This is nothing against you OP, but, dons flame suit, if she is really as dangerous as she sounds there, and she has had knowledgeable handling then in my honest opinion her value is even less than $0.
As others have said there are so many really nice, uncomplicated, sound & sane horses who have fallen on hard times out there that I would be tempted to euth this mare. I know that some people will hate me for saying so, but once she leaves your farm you have zero control over what happens to her, and she could just keep getting into worse places and situations.
Goodluck anyway, I hope you find a solution that works to everyone's best interest