There's a lot of cultural forces keeping people at jobs. We're told to never quit from everything. We're told it in school, movies, sitcoms and stories so it feel wrong and bad to quit. Especially true for work. The Office made Josh Porter the villain for quitting a failing paper company for a senior position at a successful company. And that's a feel good sitcom
Not too mention that our work is highly tied to our identities to a fault. The classic first question you ask anyone is what do you do for work. Not too mention the guilt business put on people to come in because their coworkers have to fill in. Since most people like their coworker this feels like letting them down. But it's the company letting them down by not replacing you or staffing at the correct level.
So everything you are feeling is normal especially if you have never quit a job before. It's hard but you are going to feel amazing when you do it. There's no feeling like quitting a job you hate