Feel pushed into babysitting by my family?

I currently have free time so I said I could babysit a Tuesday when one of my aunts who isn’t very nice or well liked asked if I could watch her grandkid who she’s watching because his mom is on drugs and left her with the kid for the summer. My other aunt said she couldn’t unless she was paid so I probably won’t be either. So I babysit this time and she told me I will be watching him the majority of the time on the days all summer. This wasn’t a conversation? And I didn’t say I would at all, but my mother said she agrees I shouldn’t have to but I should try to keep the peace anyways. I will have a regular job and I don’t think I want to take time off scheduled in the middle of the week. I feel sort of manipulated.