What should I do to get my friend to act normal again?

I was friends with someone let’s just call her Kate. Well I knew Kate for a long time. We knew each other since our college days. I don’t know for sure if this is the reason that there was a sudden shift in her attitude but I don’t think that the timing is a coincidence. Well usually she would be the one to do better than me. In college she always got higher grades than me. After college she always had jobs with higher salaries than me. Well I got a new job and for the first time I got a job with a salary that is higher than hers. She asked me about the salary of my new job and I told her. After that she’d often say mean and nasty remarks. Sometimes she’d say condescending remarks. For some reason she’ll try to persuade me to quit my job. She’ll say that my job seems too stressful and my boss seems bad. She never tried to persuade me to quit my previous jobs even if I didn’t like them. I just want my friend back. How can I get Kate to be normal again?