Quick rant / question

What do you do when your brothers call you mom? Let me explain.. ok well since they were born they have been around me and our mother is always gone and maybe spends an hour with them in a month. They are 8 now will be 9 in July. Most of the time I correct them and sometimes I don't catch it and answer. But she gets really mad because they call me mom on near her. I get kinda torn down when she says that I'm trying to steal her kids away from her and all I ever did was try to help her.. she was never there for me or my younger sister. I quickly had to learn to cook clean and take care of me and my sister at 6 and she is 2years younger than me. I just do the same with them showing them love and guidance something that I never had.... Am I in the wrong?