Long term sub

My colleague is a long term sub, and I am a certified teacher. I am mad that she is a long term sub and being paid more than me.

I had to go through many years of schooling to do get the position I have. I also work harder and have more responsibilities since I am a certified teacher.

How do I not feel jealous or angry about her being a long term sub? I’m a little confused about why it would make me angry anyway.