Communication help: How can I tell my old therapist that therapy with her only messed me up more, without sounding like your average “unhappy customer”? - Help.com

do you really need to tell her, cant you just walk away?
if you really feel the need to tell her id simply write it in a letter where you felt things could have been handled differently, and walk away

He should tell her for the sake of future patients.

Try to avoid accusational language, just state what she did and the consequences of those actions instead of blaming her out right for whats happened. Try to keep it objectionable and avoid personal attacks. Maybe explain how you feel she should have acted.

But what did she do exactly?

Here’s an idea, write down here what you’d write to her and we’ll give pointers.

well, you would think that but the fact is, unless she has gone against code it wont actually help other customers, they need to go by the book but at the same time be compromising with each individual patient. This is a very fine line to walk and the fact is, because they themselves are individual they wont be able to connect with each patient accordingly, thats why its important to shop around for one that you can connect with.
When you say it should be said for the sake of future clients it sounds like this therapist has done something wrong when in fact they may just not have been suited to this particular client so if thats the case, cant you just walk away, just tell them its not suited to you