Thanks. All tips are welcomed. We've probably been telling her the wrong thing. She is rebelling against the fact that she is so emotional. She sees it as something being wrong with her.
I went through this myself and it's such an awful feeling.
What I would suggest is discussing gifted over-excitabilities and be clear that the sensitivity is not a fault but rather a symptom of a gift. Make her proud of it. Then you frame the need to control her emotions as a strategic approach that will make her life easier, rather than "something she has to fix that is broken."