Not wanting my sister around my child

Is it wrong to not want my sister around my child ( I'm currently 8 weeks pregnant) considering every time she gets into an argument between me or my mom she tells my 3 year old niece that she will never see us again and we are horrible people and we don't want her !?!?!? She doesn't seem to get that she's old enough understand that stuff now and she uses her as a pawn against us like if we're rude to her we will never get to see my niece again. She's done that since she was a baby. It just makes me sick, it's not right