My SiL can be very opinionated, bossy and falls out with lots of people.
She has been horrible to me previously and now I keep her at arms length for the sake of family peace.
My brother is quite hen pecked and I'm unable to just deal with him.
She's recently asked me to start babysitting my niece and nephew overnight. My issue is this would mean dealing with the SiL again and I want to say no. AIBU to do this and if not, how do I say no without it causing more arguments.