My sister and her husband had a 5 day long trip planned, and my sister's mother was supposed to babysit the kids (4 and 7 years old). She got sick a few days before the trip, so my sister asked me to do it. I refused, because I don't really like kids, and I don't have any experience with babysitting. My niece and nephew are usually nice, but they can be really difficult sometimes (just like all kids i assume).
My sister asked me why, since I'm home all week with no plans anyways. She had asked me if I had plans for that week before asking me to babysit. If she had just asked me to babysit first, I would've lied and said I have plans. I tried to explain that I don't really know anything about kids or how to deal with them, but she got mad at me and called me selfish.
They had to cancel the trip since no one else could babysit the kids on such short notice, and my sister definitely blames me. This happened last month, and I heard that she's still mad at me from our brother. So, am I the asshole here?