VelmaMae, this must be very hard for you to work full time and raise 3 children...my mother did the same when my father died when I was 6 and I appreciate today how hard that was for her too.
If you have family that you can reach out to for help, maybe they can help you through the rough spots. Or tighten the budget until it squeaks and try to make it through. My mother always said "If I do my part, God will do the rest" and He always did.
I will keep you and your kids in my prayers, that somehow you will all stay close and get through these hard times.
Hugs