imagine you dumped a girl friend of yours, now her friend comes and asks you to be a bit more tender with her because she's been suffering a lot since you left, well here i need an expression or idiom telling that it is the least important thing you can think of and it doesnt matter at all

in my native language there is an expression used in this situation, it says "it's even less important than my balls"

well im looking for sth somehow the same
