Tired of being a mom?

Before you start bashing please read. I am on of 6 kids and the oldest . i have been a "mom" since as early as I can remember. My mom had so much on her plate i was changing diapers and bathing my younger siblings from 7 yr old and up since I was mature for my age. As I got older i practically raised them. I have 2 kids of my own and am still picking up her slack since she had more kids than she wanted and doesnt want to be a mom anymore. I do it for my sibling because i love them and they didnt ask to be brought into this world. the problem is it is affecting my own kids who are both under the age of 7. I am so burnt out I am snappy. I feel like I have been a mom my whole life but I am only 26 yrs old. What do other moms do when they are burnt out because my normal meathods like taking a hot bath arent cutting it anymore???