The best time to make a change in your life was 10 years ago, the second best time is now.
Don’t base your happiness on your achievements as compared to others. Life isn’t deterministic, every person is working with a different set of skills and circumstances. Set your own goals based on what you want to do, and work toward that.
If you don’t know what you want to do, start trying new things.
She’s had years to train up a successor, at this point it’s just blind power hungry arrogance.