The title of this thread is "need to make a decision"
I'm going to suggest stepping outside the box for a moment and agree with you, but can you be open to the idea that what you need to make a decision about isn't whether the Piano teacher is appropriate or not, but whether you would like to start changing your thinking and take steps to recover from your own judgmentalism and codependency issues.
In which Case I would suggest Step Three, Made a decision to turn our will and our lives over to the care of God as we understand God
Of course after you work step two, which is came to believe that a power greater then ourselves could restore us to sanity, of course you would have to want to be restored to sanity for that to work.
Or you could just keep doing what you are doing, that's OK too, but keep in mind if nothing changes, nothing changes