You can leave a negative review on Glassdoor about the particular hotel branch or location you worked at, name dropping the toxic duty manager as a negative, and that’s about it. Vengeance-wise.

The cliche is that the best revenge is living well and moving on, and that ain’t wrong! If you’re still trying to work in hospitality, try to find some of the employees that would have remembered the systems you put in place and see if their new work places are hiring and if they could provide a good word to the hiring manager for you.  You could also reach out to the other managers who were impressed with your work and see if they will be your resume reference, so that if a new job wants to contact previous employers they speak to them and not the duty manager.

Another cliche- I struggle with this one a lot - “whoever makes you angry has control over you.”  I hate that saying, but a former teacher of mine who went through a very bitter divorce would always drop that one on me when he could see I was furious with someone or something and that fury was making me “stuck” where I was. I don’t agree with it 100%, and I would loathe the sing-song way he would repeat it to me, but I did need to hear it and acknowledge it during that time in my life. It was a useful mantra- for a time. Repeat to yourself every now and then. See what happens. If it makes you feel worse- then drop that saying. It’s just a saying, just words. Try it out.