Driving instructor courses with the ex

Last summer I decided to finally make my dream come true and I decided to take driving instructor courses. I was very confident about this idea of mine, because I was a very good driver and everybody that drove with me was telling me that. I went to the company that I chose and I signed up for the driving instructor courses. Little did I know that I had totally bad luck, because my instructor turned out to be my ex-girlfriend. I had no idea, that she was working there, if I had known that, then I would have gone to a different place. Now I had a really hard time driving with her, and the worst part about it all was, that she had to write references for me so that I would be able to take my exam for a driving instructor. I thought myself that I was doing pretty good, but my ex-girlfriend was telling me all the time, that I did this wrong, that wrong, everything was wrong. At the end of my course she told me, that I didn"t have what it takes to become a driving instructor and that she cannot write a positive reference for me. I was totally furious, because I was sure it was just her personal opinion about me that made her decide that way. I wanted to appeal to her boss to give me a different instructor, but unfortunately it did not work out.