I remember feeling exactly like this a few years back.
Sounds like the first thing you need to do, is to let the house go a little bit and get out a bit more. Working like a slave to keep the house tidy (then having to stand back whilst everyone unravels it all again) is just pointless, heartbreaking and a complete waste of time.
How old are your eldest two children? are they old enough to start helping around the house?
I am a firm believer that children should understand about cause and effect and that they should learn to face the consequences if they don't pull their weight (I have 4 children and our house is a constant stream of activity, friends traipsing in and out and lots of mess) however I do expect the children to help out aroud the house.
My eldest 2 are expected to clean, polish and hoover their rooms, my 7 year old hangs out the washing and my youngest (aged 4) is often asked to tidy away toys, books etc.
They are all expected to help carry washing/toys upstairs and to set/clear the table at meal times and scrape plates etc.
Then there are the little things that start to build up, if one of my sons uses the loo and forgets to flush/wipe the seat etc, they are asked to come back home (if they have gone out to play) to come and sort it. I see no reason why I should have to do that, when they are perfectly capable of doing it themselves.
I picked them after school once as we needed to go to the supermarket, they all made such a fuss and complained and moaned about the fact we had to go shopping that I turned the car around and came home. They all had bread and butter for dinner that night and some fruit. The simple fact is, if we don't shop, we don't eat! and I absolutely will not drag 4 whingy children around a supermarket!
I know that this sounds strict, but we dedicate a lot of time to our children, we let all their friends come ound to play and happily share the contents of our garage/shed/toy room etc and this creates a lot of extra work for us.
Now you might think that my house sounds really well ran and tidy, infact the opposite is true, it's a chaotic mess and I have had to learn to live with it but at least the children will grow up knowing how to take care of themselves and pull their weight so to speak.
You say that your husband is under a lot of stress, fair enough, you don't necesarily expect hime to put in more then he already has, but he should at least be supportng youy in any decisions that you make with reagrds to routine, household chores etc.
Good luck with it, this phase often passes and once your youngest is at preschool, you will at least hve a bit of time to yourself.
Def try and find some local playgroups etc as they will help to break up your day and take the edge of things.
Thinking of you...