People pleaser INFJ’s, how do you navigate quitting?

I started a new job beginning of September that I’ve grown to hate. I didn’t love it when I first started. I remember being so exhausted and upset after my first full day post training. And the job is part time and I currently don’t have any health insurance and don’t have enough money to live. I can’t really find a reason to stay at this job.

But they’re way understaffed and the company is a mess. I told my boss that I might need to cut back on my hours so I can work another job I was offered in food service (amounting to full time work altogether + this other job provides benefits even for part time workers. This job could be full time if I had open availability). She said she was counting on me to stay during all the hours the office was open because again, they’re way understaffed. She told me I could come in early/stay late to get to full time hours. I didn’t ask about benefits or anything but… I’m pretty sure it would be illegal to work over 35 (?) hours a week and not be given benefits. I’m not really sure what my work would consist of if I did this and this job is already damaging my mental health at part time. I have no desire to work more hours at this job. But I’m having a hard time saying no and disappointing everyone. This situation makes me just want to quit completely as I was only going to cut back my hours as a way of being nice.

How should I go forward? Should I stay and work less hours or leave?

Another point is that one of my co-workers who operates in a manager role has been trying to leave this job for months but keeps getting sucked into staying by our manipulative boss. I feel for her so I was afraid that if I left, she wouldn’t leave. But she is also quitting next month.

Another-nother point is she will be the third person to quit since I started working there in September.