Is it worth it to keep working???

I have 3 children and a boss who doesnt care that I have them. My 8 y/o daughter has to be up at 530 in the morning and has to be dropped off at school by daycare, and then goes to daycare after school until 6, where she is then picked up by a relative and kep until 7,at which time, I pick her and take her home and then feed her and her 2 brothers,age 13 & 14, who are alone after school everyday from 4-730. My husband, their father, doesn't really make a whole lot of money for us to live on alone, but my work hours are starting to affect the kids, and I'm starting to think it isn't worth it to keep working. Would it be better to quit and look for another job w/ a better schedule, or stick w/ it, while looking for new work. I'm getting so frustrated and have to talk myself into going to work everyday now, and I never had to, but the boss changed my schedule, and gave me no choice. Help!!!!!