Saturday is here!

What a long week!  EC had the week off school for "mid-term break."  It was really hard to juggle both kids all day.  EC needs to get out of the house and be around other kids.  A needs to take one or sometimes two naps a day.  Those two needs don't always mesh well.  By the end of every day this week, I was so tired of whining and crying and tantrums and fighting.  I guess this makes me feel really good about our decision to put EC in full-time school here.  She needs to be there, and we need her to be there!
So, by the evening yesterday, I was beat.  I had a headache that I had been meaning to take some ibuprofin for all day.  I had no food in the fridge or the cupboards, I had 2 very whiny kids.  I had A throwing the little food we had in the house on the floor.  I had EC stomping her feet and throwing a fit that we weren't going to make it to the playground before dark.  Cue: Jones walking in from a day of school.
How do other people do it?  How do you maintain a cheerful disposition when your world is chaos?  How do you act happy when your husband comes home and all you really want to do is yell, "Tag, you're it!" and run out of the house for freedom?  I'm really asking this question seriously.  I really need to know.
You see, I'm not one of those stepford wives.  I'm not Donna Reed.  I'm not making it look easy and good and stress-free.  I'm the one who did run out of the house when Jones came home.  I went to check our mail at the college.  I went to the East-West Provisions shop around the corner and bought some time.  I came home and ordered Indian take-away.  I unloaded all my frustrations on my husband.  I cleaned the curry off the counter tops.  I went to bed unhappy.
This morning, I was wide awake at 5am, wondering how to make today any different.  I haven't figured that out.  Luckily, my husband did hear my list of complaints (no time for myself, can't ever eat breakfast, no peace with the kids, someone always whining and bothering me, etc)  Jones took the kids out for an adventure to get A's haircut this morning.  I'm home by myself with some tea and my computer.  Time to blog, time to shop for the kids Christmas presents on ebay, time to breathe.
I still wonder if anyone can help me out here.  What do you do to get some time for your own sanity?  How do you love your children, but teach them that you aren't a human doormat?  How do you keep doing it all, day after day after day?  How do you not lose yourself in your role as mother, cleaner, cook, nose-wiper, poopy diaper changer, never-getting-to-sit-and-enjoy-a-meal-that-you-cooked person?
Thanks in advance for any tips.  I need them!