AITAH for refusing to change diapers of brother's kid?

I am childfree and single by choice. I hate diaper changing or cleaning kids. Once my sister left her baby with me and I found it most disgusting. I gift the kids and spend the time with them only, if someone is supervising side by side

So my brother and his wife were going somewhere ( only couple of homes away ) for couple of hours and I told them I won't babysit if they expect me to clean the kid. I made it clear.

He came to my home and left the kids urgently ( 1f,3m ). And didn't even let me speak and drove away.

I was pissed. And few minutes later niece pooped. I messaged them urgently to come and clean because I wasn't doing it. They didn't believe me. I kept sending and finally they arrived 15 mins later and cleaned her and screamed at me. I screamed back at them. Telling its not my responsibility to clean their kids. And hire a nanny for that. I would've cleaned her if they hadn't come. But still i find it disgusting

Now my whole family is calling me an ah. Which I don't think I am

Aitah?