DEAR ABBY: I am glad you agreed with Grandma! Her 11-year-old grandson and 8-year-old granddaughter should not be sleeping with their father -- or each other.

When I was 10 years old, my 12-year-old brother and I were forced to sleep together in one bed at a cousin's house. In the middle of the night I found my brother on top of me! He molested me until I was 17 years old, and to this day I have not told a soul -- including my husband, and we have been married for nearly 20 years.

I am so ashamed of it, that even now if I think of it for a few minutes, it makes me physically ill!

Please, parents, friends, relatives -- don't let this happen to children. I came from a very respectable family, and I am sure that nobody would believe that this happened to me. But it did! -- KEEPING MY SECRET

DEAR KEEPING: Please, don't keep your secret any longer. Contact your local rape crisis center and inquire about counseling and support groups for people who have kept this kind of secret for years. You have nothing to be ashamed of -- you were a victim. Victims should bear no guilt.

In counseling, you will learn that in order to heal, you must confront your brother after all these years and tell him how much pain he has caused you. With counseling this can be accomplished. Trust me. Please get counseling, then write again and let me know how you are. I care.

DEAR ABBY: I've read your column for years and have never seen a problem quite like the one I have. It all started when my son bought one of those video cameras. Since he bought it, he's been driving everyone crazy sticking that camera in their faces.

He wants me and my ex-wife (his mother) to act like we're a lovey-dovey couple before his camera, so my granddaughter (his daughter) can watch it someday and see her grandma and grandpa when they were "happy" together.

Abby, we were divorced 14 years ago because of her infidelity, and the thought of pretending to be civil with that woman is more than I can stomach. Of course, she's all for it, so now I'm the bad guy. Normally, we can't stand the sight of each other, and I think the idea of pretending is ridiculous.

Both of our current spouses have said they wouldn't mind. Any suggestions? -- RETIRED IN SAN DIEGO

DEAR RETIRED: Unless both you and your "ex" are Academy Award-winning performers, you'd be foolish to act like you're a "lovey-dovey" couple before a camera. I agree with you -- the idea of "pretending" is indeed ridiculous. It is also dishonest to attempt to rewrite history.

CONFIDENTIAL TO IN LOVE IN HOUSTON: Send your married man back to his wife and children, and tell him to stay there. You can't build happiness on the misery of others. And by the way, nobody "falls in love" with a person who is married; they either kick the fence down or climb over it.

To get Abby's booklet "How to Write Letters for All Occasions," send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Letter Booklet, P.O. Box 447, Mount Morris, Ill. 61054. (Postage is included.)

DEAR ABBY: I am writing in response to the couple in Anchorage who were torn over whether or not to keep the $42 the husband found in the glove compartment of the used car they had recently purchased.

They have no legal responsibility to return the money to the car's original owner. To illustrate, here's a similar case that went to the Supreme Court in 1981: In the case of the City of Everett v. the Estate of Sumstad, the Mitchells were a couple who purchased a used safe at an auction for $50. The safe had previously belonged to the Sumstad estate and contained a locked inside compartment. The Mitchells had a locksmith open the compartment and discovered $32,207 inside.

The Everett police impounded the money and brought an action against both the Sumstad estate and the Mitchells to determine the owner of the money. The trial court decided in favor of the estate, but in appeal, summary judgment was for the Mitchells.

Since the Mitchells understood the sale was final, and the auctioneer reserved no rights of the estate to any contents of the safe, the reasonable conclusion is that the auctioneer objectively intended to sell both the safe and its contents, and that both parties mutually assented to the sale. Therefore, the Anchorage couple should feel no guilt in keeping the $42, since the Supreme Court ruled that the Mitchells could keep $32,207. -- KNOWS THE LAW

DEAR KNOWS: Surely you also must know that that which is legal is not always moral. I rest my case.

DEAR ABBY: The first time you quoted "The Reading Mother," I meant to write to you; when you did it again today, I decided I would not fail this time.

Why not a reading father? My three sons received bedtime readings from the time they were small until almost through high school. I, their father, was the reader; I love books, and I enjoyed the material at least as much as they did.

We got through the Alice books, "Gulliver's Travels," "Huckleberry Finn," "Lord of the Rings," and scores of others.

I was in medical school and psychiatric residency training during many of these years, and the hours spent reading to my children were a welcome relief to me, as well as an introduction to the world of literature to them.

I recommend reading aloud to children of all ages by either parent. -- ROB HARDY, CHIEF, MENTAL HEALTH SERVICES, R.A.F., LAKENHEATH, UNITED KINGDOM

DEAR DR. HARDY: I am printing your letter in the interest of fairness to those fathers who read to their children. Although their numbers may not be as great as mothers, they deserve to be counted.

CONFIDENTIAL TO DESPERATE IN CHICAGO: "The darkest hour in a man's life is when he sits down to plan how to get money without earning it." -- HORACE GREELEY

People are eating them up! For Abby's favorite recipes, send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Cookbooklet, P.O. Box 447, Mount Morris, Ill. 61054. (Postage is included.)

DEAR ABBY: I am 21 1/2 years old and was married when I was 20. I thought at the time I was doing the right thing, but now, after a year and a half of marriage, I realize it was a mistake. I was too young to get married.

My husband and I disagreed on too many things, so now we are getting a divorce. He doesn't want it, but he says if I pay for it, he will sign all the required papers. We have nothing to divide. No house, no car, no money and no kids. Nothing to fight over.

Now for my problem: I went to a legal clinic and they told me there wasn't any "no-fault divorce" in Cook County, Ill., which is where we live. This means I will have to go to court and claim "mental cruelty."

Abby, there was no mental cruelty, so why do I have to go to court and lie -- especially since my husband agreed to cooperate? Isn't there someplace that we could go and just sign some papers and be divorced? Why must I point a finger of blame at a perfectly nice man? The marriage was MY mistake.

Also, I would like to know why a divorce should cost so much? I was quoted a figure of $970. There is nothing to divide up, and my husband is not going to contest the divorce. Isn't there a cheaper and easier way? -- NOBODY'S FAULT

DEAR NOBODY'S FAULT: A cheaper divorce would be available through your legal aid society -- only if you are unemployed.

According to Dorothy B. Johnson, attorney at law and chairperson of the Chicago Bar Association Matrimonial Law Committee:

"Since July 1, 1984, there has been another ground for dissolution of marriage in Illinois, which you and your spouse may find more suitable: 'irreconcilable differences.'

"As for the cost of your divorce, the rate you were quoted is not out of line for the greater Chicago area."

DEAR ABBY: The letter from a woman who had witnessed a father abusing his young son in a department store, and she didn't know what to do or say, bothered me. You seemed to be sympathetic with the abuser and suggested that she could have said, "I know how you must feel -- shopping with children isn't easy," which would seem to give approval to the father's actions.

The other day, I witnessed a similar situation involving a young mother in a checkout line in a supermarket. Her child had obviously misbehaved and the mother was berating him with some harsh words that can hurt a child more than physical blows!

A woman in line in front of them turned around and delivered what I thought was the perfect remark: "I'll give you a dollar for him!"

That one sentence reminded the young mother of the value of her child.

I wish I had said it. -- SYLVIA E., LOS ANGELES

DEAR ABBY: I have never written to you before, but after reading about the old gentleman who is still making love often at the age of 85, I took the newspaper out of the trash can three times to make sure I had read it correctly.

I would sure like to hear his wife's side of this story. I'll bet she is sick to death of it. Or maybe she is like me, going through the motions and faking it.

I am a 65-year-old woman married to the most wonderful man in the world, and I have been faking it for years. How many letters have you gotten on this one? I would love to know. -- "B" IN DALLAS

DEAR "B": Thus far, only a few, but I would welcome letters or postcards (unsigned, of course) from other females who have been "faking it" for years.

"How to Be Popular" is an excellent guide to becoming a better conversationalist and a more attractive person. To order, send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Popularity Booklet, P.O. Box 447, Mount Morris, Ill. 61054. (Postage is included.)