LOVE this! I agree!!!Thank you for sharing this.
Please do not underestimate the risk for long term damage to your daughter in this environment.
The silver lining option (painfully difficult, but a very important lesson in self-respect):
As a parent, shoulder the "Tough Love" decision and decisively pull your child out of the situation.
Let her know that at no point in her life is it ever acceptable for anyone to treat her like this.
Use the term "Abuse" with your daughter. Explain how people use it to gain control over others.
Now she knows what emotional abuse looks like, and to avoid people who treat her like this.
Her "Short term" anger directed at a parent... A tumultuous path leading to lifetime of self-respect.
Informing the coach, afterwards, as to why she left sometimes can facilitate change - but I wouldn't hold my breath.
If a parent's thoughtful rationale based on principles is carefully explained, an extremely difficult, unilateral decision by a parent tends to be deeply respected by the child - albeit sometimes much later in life.