trust betrayed

[Bonbon27]

I have been having personal training with a martial arts instructor. I told the instructor something very personal and sensitive. I asked him if he has told anyone? He said "no" at first. I then asked if he has told anyone other instructors. He then confessed another instructor knows. I have not given any permission for this.
I was obviously very upset about this and it has caused me a great deal of distress. I then confronted him about it another day and he said he couldn't remember what he said.
I feel he has betrayed my trust, I can't trust the other instructor.
I spoke to the other instructor about this and there response to this was "he didn't actually tell me anything". Not sure I believe this, feel they are protecting themselves.
Am I right that he has breached confidentiality? Is it against ethics as you are meant to trust and respect your instructors.
Any thoughts please,

Agree with @UncannyFanny reporting to the martial arts body?
and does a general gym have a safeguarding lead?

If she’s told her instructor something sensitive about her health or her personal background then it’s a breach of industry ethics for her instructor to share the information without first advising OP that he feels the information has to be shared, explaining why that is, and confirming who he will be sharing it with. If he doesn’t know this, then he needs some refresher training around how to handle sensitive information in the workplace. He isn’t her friend, he’s a professional.

A gym or martial arts studio should have a safeguarding lead, yes. There should be clear policies and procedures in place for the protection of children and vulnerable adults and for promoting a wider culture of safety and accountability.

You're massively overreacting

I can't really envisage a situation where you would tell a PT something so personal. Surely, you go to the gym, do training, talk about training. Where does the super personal chat come in?

And how do you even know he shared that information? Are you constantly asking him about it? Or is he encouraging this kind of disclosure?

I think you're being unreasonable to expect therapist level privacy from a PT. It's not something they're trained to deal with either.