I was told to train the person hired above me

Dear Delyara, I applied for a management role after twelve years in the department. I had been covering many of the responsibilities informally for eighteen months. They hired someone from outside. Fine. That happens. Yesterday, my director asked me to spend six weeks training him because “you know the operation better than anyone.” I almost laughed. Apparently I know the work well enough to teach the manager but not well enough to become one. The new man is polite and clearly uncomfortable. He keeps saying, “I hope this isn’t awkward.” It is. Today, I showed him how to handle an escalation process I designed myself. He took notes. Next month, he will assess my performance using the process I built. My wife says I should leave. I have a mortgage, two children, and no guarantee another employer will value me differently. At lunch, I ate in my car because I could not bear people asking how training was going. The worst part is that I want him to succeed because if he fails, management may decide the whole team is the problem. I am teaching a stranger how to stand on the rung I spent years reaching for.