I'm going to come to work sick
Why do you think that you should go if you are sick?
I'm going to come to work sick, because I want to quit my job on bad terms.
Quitting your job if you hate it is something that you need to do, but not while sick. Wait until you get better and go to the jobsite. That way you won't infect others there and make them hate you for it.
What if I feel better and I have a hunch they are planning to screw me over and they might fire me.
I think that if you think that you are ill, you should just stay home. It is not okay that you are going to work when you are sick.