Not sure of the whole situation but here (USA legal system and mental health system) if a mental health person is accused of wrong doing they have the right to face their accuser and they have the right to defend their self and produce evidence that shows they did nothing wrong.

If there is evidence in the file like documentation of the sessions, that shows they did nothing wrong they have every right to show that evidence to their supervisor, the ethics board and their lawyer. In their defense they have the right to also show things like any threats or derogatory comments you made verbally, written or recorded against the accused that you made at any point from the time you began working with them to the time you ended your work relationship with them.

There is HIPPA and HIPAA privacy laws but that doesn't protect the client in therapy from the legal system. Each state and mental health agency has rules and guidelines that allow them to release the files in situations like suicide, homicide, threatening behavior, legal situations. The privacy laws are there so that professionals cant go to your family and friends or other professionals for just any thing and tell them about your business.