My trainee has been asked to supervise me

Dear Delyara, I trained Marcus when he joined our department six years ago. He sat beside me for months, wrote down everything I said, and called me whenever something went wrong after hours. Today, management announced a restructuring. Marcus is now my supervisor. I smiled, shook his hand, and told him he deserved the opportunity. Part of me means that. He is smart, hardworking, and good with people. Another part of me feels humiliated every time his calendar invitation arrives with the words “performance check-in.” I am fifty-seven. Marcus is thirty-two. I know age alone does not entitle me to promotion. What hurts is that I applied for the same role and was told I lacked “future-facing leadership energy.” Nobody could explain what that meant. This afternoon, Marcus asked me to show him how to correct a reporting error because he still does not know the system well enough. I showed him. Then he reminded me that next quarter he will be reviewing whether my position remains necessary. I went to the restroom and stood in a stall with my fist against my mouth because I could not decide whether I was angry at him, the company, myself, or the years I spent believing being useful would eventually become the same thing as being valued.