I am a 3-shift nurse and I have a concern

It wasn't the schedule I wanted, but since it's a workplace, I did as I was told and accepted what was given, but I couldn't endure it. When I resigned, I inquired about the night shift differential, and it got distorted into a situation where they claimed I said I would report them if they didn't pay me. Because of this, for my scheduled time off on the 11th of this month, I was told to only take 6 days off, and since 4 of those were "on-call" (which is practically the same as being on duty), I felt like I had almost no days off and my body was being ground down.
What I got in return was being told to sign a document stating that I worked with mutual consent, just in case there might be legal issues later, even though there are none. I had worked silently and with all my heart, promising to do my best when I joined this department, so I did tell them directly, "Is this how you treat me?"
I am truly forcing myself to go to work right now and it is so difficult. I wonder if I should maintain professional courtesy when the other party treats me like a disposable commodity, especially since I have worked here for over a year.
For my own sake, I think it is right to work until September, but
I have a lot on my mind.