Should I go ahead and quit?

First off, I want to say I work for a good employer, but I feel I'm not cut out for the job. I feel I cant effectively do my job in part because I've had crisis after crisis, issues in my home life, and I was asked to do three times the amount of stuff with no help. I have been a sub for many years. My job only was  to execute the main teacher's plans. I was asked to be a long term middle school Math teacher for 6,7,8 grade mixed class where none of the kids are on grade level but I was asked to teach 30 kids. 10 each class some as low as 1st grade no assistance w grade level material. Then, I was told to make up lesson plans for that class and an elective made up class. I was supposed to come up with plus teach typing no experience. 3 classes as a long term sub, not before the classes started like almost 2 months in. I'm a single Mom of 3 one child w a severe mental disability and CP. All 3 of my kids including me has been in car accidents needing therapy, it's my daughter's senior year, my car was totaled by a semi so I spent half the semester looking for one, I was in the hospital for sepsis, found out my fiance was in another full blown relationship. No time. . We were almost homeless because my landlord couldn't pay the mortgage. I havent been able to grade papers. I don't know how to put them in.. I was given a test and left to my own devices. I cant keep up. I called in sick. I don't feel good but it's not physical. .