Is there such a thing as a "good resignation"? I don't want to be polite, but should I be?

It wasn't the work schedule I wanted, but since it's a workplace, I did as I was told and took what I was given, but I just couldn't endure it anymore. Even when resigning, I inquired about the night shift nursing allowance, and it got distorted into a situation where they claimed I said I would report them if they didn't pay it. Because of this, instead of having my scheduled days off on the 11th of this month, I was told to work and only take 6 days off (which is practically no different from working straight through), and since 4 of those were my scheduled days off, I felt like I had almost no rest and my body was being ground down.
They told me that while there are no legal issues, to prevent any future problems, I should sign a document stating that I worked with mutual consent. I had worked with all my heart since joining this department and worked silently, but I ended up asking them directly if this is how they repay such sincerity. If they were going to file a complaint with the Labor Office, they should have just let me quit sooner.
I am truly struggling and forcing myself to go to work right now, but since the other party treats me like a disposable commodity, I wonder if I really need to be polite. Then again, I've worked here for over a year.
I feel like working until September is the right thing to do for my own sake, but
I have a lot on my mind.