I suggest you find a way to relish the things you get to do to care for and raise them. Maybe start with the idea of "i get to do this" not "I have to do this". Trust me time flies by and those years in the future you are longing for now when your kids are grown up so you can have more of your life back you will be wishing you had a few more moments of the current chaos you are mired in.
It's not supposed to be easy. We all have our moments but relish it before it passes you by without taking the time to appreciate it.