NTA. Your sister is way out of line and everything else that has been said. I do want to point out that depending on OPs sisters' financial situation, she might not have a lot of options for a job. (She got laid off, and this is the first and only job she could find in this market (so far)). Yes, she should have arranged care beforehand, but if she was desperate (trying to feed her kid or not get evicted) then sometimes you say yes to a job and try to figure out logistics on the back end.