Speaking to The Mirror, the ITV talent show contestant insisted however that she has since become "a different person".
She explained: "At school I was bullied - and I did bully people myself. I was a playground bully. When I was younger, the stuff that I had to deal with was tough."
Criticising judge Tulisa Contostavlos, the 19-year-old continued: "Being called an X Factor bully on national TV was not fair. I know I am not a bad person. Tulisa hurt my feelings because there's always two sides to the story.
"I'm here for the music. Things do get heated backstage, but I'm going to take on board what they've said and take it in my stride."
Bryan added: "I still feel really sorry for any hurt I may have caused in the past, but I have tried really hard to turn my life around and become a better person.
"I love music and this is my passion and I really want to make a difference to people's lives. Every day I think positively, and try to push negativity away.
"Everyone has a past and people make mistakes - I'm proud to say that I've learnt from mine and I have moved on."
Fellow acts Johnny Robinson and Sami Brookes have recently stood up for the star.