IT'S HOT and my car is not working and I'm walking to work. From my home over Scheeles Market in Georgetown to 18th and M. Two blocks from home, my sandal breaks. Life is a series of rearrangements. After a 10-year marriage that ended in divorce, I have learned that much.

Starting out again, I stopped at Lorna's for coffee. She controls the informal network which operates among Georgetown families, swapping children's clothes and shoes when they are outgrown. I tell Lorna my boys need more tennis shoes for camp.

We discuss a favorite topic, Georgetown property, and President Carter. His loyalty question is offensive to me - and my great-great-great-grandfather wrote the national anthem.

For an ex-wife with two children and no marketable skills, finding a job was a problem. A friend at Georgetown Employment let me practice on her office typewriter and tested me until I could pass. She found me the ideal job - the chairman of a major accounting firm needed a secretary who could help set up special arrangements for social events and executive meetings, but who didn't need fast secretarial skills. That was me. Now I could pay the rent.

At the office, I find a message from a White House friend, "Lunch is off for today." No surprise, under the circumstances. I help three writers, here from our New York office, get settled in the luxurious executive suite - "The Taj."

Going home, I bump into Peter, 8, rushing out of Scheeles in brief nylon bathing suit he rarely takes off, looking guilty - clutching chocolates. What tale did he tell to get past the Scheeles? (I wish they would sell spinach cookies!)

While Fred Scheele grinds our hamburger, I relax in the visitors chair beside his butcher block. His family has owned this market for over 80 years - his father was the unofficial mayor of Georgetown. When my divorce came and left me with little money and no job, the Scheeles let us move into the apartment upstairs, helped us paint and repair, build a garden and made us part of their family.

Dishes done by hand; boys happily playing backgammon. Ed Keller, an old friend back from a tour in Brussels with the State Department, comes to pay his rent. I bought an apartment with a partner on borrowed money, furnished it and rented it to Ed. My first experience in free enterprise. TUESDAY

Representatives from big oil companies are gathered in the reception area as I walk in. I must identify them somehow, and introduce them in the conference room. No list of names, no idea how many for luncheon, need another projector - and one of our team is late for this meeting.

George Scheele phones me: Peter was late for the bus, and missed his ride to camp. I suggest Peter go down the street to Rose Park where children from a variety of backgrounds play under the strict supervision of Big Ron and Mrs. Woods, whose authority is accepted without question. Mrs. Woods once told a boy who behaved badly to leave the park, and sent him to my house when his parents couldn't be reached. She knew that if I wasn't there, the Scheeles would be. Big Ron's speciality is field sports, but one day I found him gently snipping red tissue paper into a costume for Andrew, 9, who was to be a tomato in the local parade.

Peter calls at noon, bored. He wants to swim in a neighbor's pool, but no one can supervise. The Scheeles offer him a job, sweeping and pulling weeds. His answer: "There are just two things I hate - sweeping, and pulling weeds!"

After work, stop at Second Hand Rose, owned by friends (one is an old schoolmate from the 1950s) to buy $6 gold evening sandals they found for me to wear to dinner dance tonight. Two of my best friends, married one week, will be at my table. (Must find a great present for them.)

Petie, a student living with us, who helps the children in exchange for room and board, has organized dinner and an evening of tennis for the boys. Delighted to be included in a grownup's doubles game, they have dressed in clean, white shorts for the event. WEDNESDAY

Today Peter's bus is late and my time is slipping. Must get to Volvo repair on 15th Street before 8:30 so that I can get my car back today. It needs serious, two-day repair. Bob, the owner, is sympathetic about the expense, points out an old car on the lot that he has kept going for 20 years.

Walk a new route to work planning a quiet morning. The usual phone calls, until, "This is the camp calling. Andrew has had a riding accident." Please, God, not his head. They say it's ankle so I relax for a minute until I remember that my car is in the shop. A friend lends me his car for the rescue.

The camp has had a doctor check him, and Andrew is the happy center of attention by the time I get there. My role as glamorous mother-to-the-rescue is shot. All he wants is a Coke. At home, he limps into Scheeles for a hero's welcome. I bring him the telephone, a copy of "Born Free," all the ice I can find to keep the swelling down and a peanut butter sandwich.

Was I only away from the office for two hours? When I return, the tranquil atmosphere is jolting - soft carpets, art work hanging straight, everyone acting normal.

Boys sleeping in bathing suits again. Why do I buy pajamas? I wash my hair. I'm the one who needs care. Ignore the letters, laundry, dishes and phone messages, collapse in front of the TV. Why do I say I never watch TV? THURSDAY

We can't find shoes to fit over Andrew's swollen ankle. He digs out bedroom slippers and is ready to go. The boys have their daily argument on the front steps, shouting for me. I'm upstairs in my underwear and can't come out. I shout out the window for them to cool it or they will disturb the peace.

Skip lunch to appear at the Naturalization office on behalf of Hossein, an Iranian friend. Only in America would an Irish Catholic and a German Jew stand up together for a Moslem from Iran to join us in citizenship.

The office is quiet, summer is here and the chairman is away. Time to do correspondence, get caterers' bills paid and consider drafting a request for a few hours' time off to take a real estate course. Could I manage night classes? Better do it - inflation is squeezing me and I need a second career.

Neighbors invite us to swim in their pool. Then home with the boys to cook dinner over charcoal on the deck. Make plans to spend weekend at a mountain resort near Washington. Three generations of the same families swim, play tennis and golf there in a turn-of-the-century setting. FRIDAY

The first phone call at the office is from Mattie, the maid at the corporate apartment. "The icemaker broke and the whole front hall is flooded. And someone put his car in the chairman's parking space."

I make arrangements to get the floor fixed, find the owner of the car and ask him to move it and request a check to pay Mattie. Then plan the menu for the chairman's dinner party next week, order the wine and make up the place cards. Don't forget the flowers.

Glory, hallelujiah, I'm taking the afternoon off!Get the car from Bob Smith's repair at noon, and stop at Scheeles for one peach and to let them know I'm going to Peter's camp for Awards Day. Drop load of clothes at the laundromat and drive to Seneca.

Peter gives me grand tour, runs the marathon and gets awards. Together we retrieve his collection of towels, jeans and old tennis shoes, dirty, torn and soaked, and start for home just as a rainstorm begins.

Safely home, we unload and store sport equipment, hide the dirty towels and stack library books to return. I give haircuts to both boys and Jingles, the dog. We bathe and dress.

Twenty are coming for an after-art-opening dinner. Free drinks and hors d'oeuvres. One tennis friend, a Georgetown caterer, has made the perfect chicken salad and another has made chocolate mousse. Tables are set in the garden with pink flowered table clothes bought for next-to-nothing after the Corcoran Ball, and the garden is lit with candles.

It's eight o'clock. The weekend is here, and we are ready. CAPTION: Picture, Elizabeth Wainwright is a third-generation Washingtonian who was a world traveler living in a 12-room historical Georgetown house. She now is a working mother and head of household living in an apartment over the local grocery.