I have come to a crossroad

I finally thought that my employee who has been torturing the rest of my staff was leaving, she resigned on Monday and then yesterday one of the docs wants to keep her so she is fighting tooth and nail for her. What do I do, truthfully if she stays she can be an assest but she is miserable, so it isn't worth a damn. If she stays I may lose two other people, and really I don't want to stay if she does. Do I help and encourage the others to leave? Yes, as a good manager I would let them go gracefully because I totally understand their needs to be happy. Do I stay? This could be an opportunity for later, what do I do?? I write because I can't scream and I am tooooo damn tired. I wish I knew the answer.