Did I [30M] make a mistake [26F] by canceling our affiliation?

I’ve been taking private music lessons from a woman for the last six months or so. For the last two months, I’ve started to grow feelings for her. She’s never shown any signs however, always being professional.

Here’s where the problem enters the picture: I’m already in a relationship since a few years back. Consequently, I’ve had a very bad conscience towards my current partner. I understand that it’s natural to develop temporary feelings for other people. But I know that if my teacher would ask me if I wanted to hang outside of the lessons, I wouldn’t hesitate. And that eventually could lead to cheating, which I’m obviously very much against. I don’t think I would take the initiative, but still. And because I’ve been thinking about her more than anything else really as of late, I decided that the best thing to do is to quit the lessons and just try to move on. And so I did. Told her that I couldn’t continue on with the lessons. She handled it just fine and didn’t push me into explaining why.

Now I’m feeling bad about the whole situation. Not only did I lose a great teacher, but also a friend.

I may also add that my current relationship isn’t going that well as we’ve both grown apart from each other and it’s probably just a matter of time before we separate.

Did I overreact?

TL;DR. Canceled a relationship with a woman that I started to develop feelings for her because I’m already in a relationship, but may have overreacted.