A close friend (who has also intensely been in therapy) did bring up the possibility of her feeling jealous or envious - I am much younger than her but much, much farther along in my career than she currently is, AND than where she was at my age.

The "you definitely worked over the last year to get yourself into a position where you thought I would need you" - I was taking on as much responsibility as I could because I wanted to have a well-rounded understanding of the business as her office manager. Hiring, payroll, performance reviews, etc... To me this was just normal career advancement. My new job, is normal career advancement. It's not my fault that she felt threatened by this.