Vent girl...let it all out....everybody needs a little ME(destress) time.Even if its only 30 minutes. Thats something your not getting. You can only do so much. there are some good suggestions here(even from the ones that cant read)

Take a step back ...look and see if you can make some changes in your life style(even small ones) to help destress your life a little.
(My opinion) When we truly reach our breaking point we usually do what we have to do to make it. Your not a quitter... look at all YOU are doing (and YOU are doing it) even tho its hard you should still be proud of all YOU are doing. Those girls may not appreciate it now.... but I bet they will when their older. You may be the only role model they have.
when they are older and come up and thank you for all you have done will it have been worth it? (of course it doesnt help now)
SMILE