Free day or take unpaid time off ?

My sister is angry with me because my job offered us to opportunity to stay on all day but we have no workload or take unpaid leave. Before this job I have been broke for the last year July 6th 2023 . I got fired from my call center job and couldn’t find a decent job that would allow me to attend to my ASD son. Before this my sister had no problem watching my kids now she is saying oh I have school work etc I need to catch up on , I’m like why didn’t you tell me ? I could keep them but she insisted she’ll watch them . I am making 20+ an hour school is literally in two weeks plus my son’s birthday . I couldn’t afford to get anything for but now I have a job and I get paid the week before his bday . Why wouldn’t I take the time Am I the asshole ? I literally been surviving off of government benefits . Please note she is only watching them for less than 2 hours and yet she is making a big ass fuss about because she wanted me to take the Unpaid. Also please note I just started this job last week and she said “ don’t put the kids in daycare I’ll watch them “ but you doing all this ? Really their dad had an interview today this is the only reason she is watching them , this is actually her second day since I started 07/22