Do you think I'm not fit to be a mother if I occasionally go out for a drink with a friend while leaving my small child with a babysitter at night?
ご質問ありがとうございます。
"Do you think I'm not fit to be a mother"=「私には母親である資格はないと思う?」
"if I occasionally go out for a drink with a friend"=「もし私がときどき友人と飲みに行ったら」
"while leaving my small child with a babysitter at night?"=「幼い子をシッターに夜、預けている間。」
ご参考までに。