When DH and I were married almost 20 years ago, I had 4 kids and he had 3. We each had custody, so we ended up with 7 kids at home! Five of them were in grade school, so you know our house was a mad house!!
We both worked full time in our store, 12 hrs days, and I did all the running with the kids also.
Some how we survived, all went on to college and now we have an empty house, just the 2 of us!
The time will go bye, and they will get older, and you will survive, even though there will be times when you won't think so.
What you really need is a little time for yourself.
Sit them down to watch a movie or a show, I know it's not a popular thing to let the TV baby sit, but sometimes you just have to have a little time to yourself!
I don't know their ages, but you can also break them up in pairs, to play a board game together. 2 is easier to control than 4!
Just some suggestions, but you need to find a way to have a little time for yourself, you are no good to anyone else if you don't take care of yourself, and there is nothing wrong with being selfish some times.
When you have had alone time, then you are more able to deal.
Good luck, and remember, This too shall Pass!!
:D
Ninnie