OOOOh, I know how you feel! You shouldn't have quit though. You should have beat them at their own game. Thay wanted you to quit, so they could tell people you didn't work out because you were not reliable....now when you open your studio.... you won't look so good.
But, I completely feel for you. it is so hard. I went to the same school from the time I was in 6th grade until I graduated. I was their top dancer from the time I was about 15 -18. Then, I went to school, got a degree in dance and came back nd taught for them for 3 years. They "lovedme". I taught all of their advanced classes and they even used to have me show the other teachers some of my techniques to teaching. During the summers, I travelled and studied as much dance as I could, but always did right by them. The problem was, I couldn't make a living off the hours they gave me and always had to wait tables or find a second job. I understood, but I didn't want to wait tables. So, after three years, I moved to New York and took classes down there. I came back that October (not really liking NY), and immediately came to them to see if they needed a teacher. They had of course already written their schedule.... no big deal. I decided to travel around the US taking classes different places.....and then returned and opened a school 50 miles from them...and my family! I called them to tell them I would be doing it, sent them a card.... nothing. They never even acknowledged that I had opened. One of their teachers is a friend of mine.....and they talk badly about me all the time. She asked them why they couldn't be happy for me.... and they just grumbled.... that she needed to understand that doors go two ways, and that I shouldn't be trying to compete with them! Some owners think you owe them. I think they just make themselves look bad.