Q.A disturbing incident occurred recently between my elementary school-age daughter and my husband. He was nude in our bed when he pulled our daughter under the covers with him and held her tightly while I was out of the room. When I came back, my daughter was trying to get away from him and was telling my husband to let her go.

She was obviously upset, but he laughed and told me that they were having some early-morning tickling. Other incidents have occurred, which I believe were innocent but also seemed inappropriate. My husband sometimes "teases" our son by holding him upside down or hugging him very tightly until he gets upset or cries, then he tells the boy that he isn't hurt, or has no reason to be upset, or he stamps away, acting hurt or angry himself.

I think children need privacy and that they have the right to tell their parents -- or anyone else -- when to stop and that their parents must respect their wishes.

How do I let my husband know that the children have the right to resist any physical activity they don't like or the closeness he wants at that moment? I don't want him to feel that I am judging him.

A.Actually, you are judging your husband, which is the proper, responsible thing to do.

You are his wife and his friend, but you are also your children's protector, and their interests come first. It doesn't matter whether they should -- or should not -- be upset or hurt by his behavior. It is enough that they are, and their feelings must be respected.

In fact, all children would be scared by this rough handling, particularly if it was administered by their own fathers. Parents have a tremendous amount of power because their children love them so much, and even a slightly raised voice can alarm a little one.

Your husband's sadistic -- and sexual -- behavior goes much farther, however, and it's way off base. He is exploiting your children.

This is what abuse is all about -- the cavalier use of one person to make the other person feel good. In his heart your husband must know that his behavior is wrong, and so do the children. That's why he reacts so strongly when they get upset, and why they resist him so much. In time they will know how to defend themselves better, but they must depend on you now. Tell your children, flatly and positively, that you are on their side and that you don't like this behavior any more than they do; that no one is allowed to tease them or hold them upside down or grab them under the covers -- not even their daddy -- especially when he's in the nude.

Tell them it may be a while before their father realizes how much his behavior upsets them, so they shouldn't be alone with him when he's in one of his "playful moods," and they should call you right away if he tries anything.

And then talk to your husband before there is one more incident. He needs to know that he is frightening his own children, and that you cannot permit it. If you're gentle enough, he may listen to you.

If he doesn't agree, or if he tries to continue his behavior, ask him to go to the pediatrician with you -- or go alone -- and see what he says. Even though a doctor or a therapist is required to call the child protection services if he suspects abuse, this wouldn't be a bad thing. One way or another, you must defend your children.

You may think these measures are extreme or that it's more dangerous to rock the family boat than to let it drift along, but it's better to intervene than to let the situation continue and perhaps get worse.

Sex abuse usually begins with small incidents and is frighteningly common among schoolchildren, especially around the ages of 8 to 11.

You'd never forgive yourself if this problem escalated, nor would the children grow up as strong as nature intended. Abuse can turn teenagers into runaways or lead them to drugs or into a depression that lasts for years, and at the least it destroys their self-esteem. Nor does the pain go away.

Grown children are still devastated by childhood abuse -- even if it was relatively mild -- and they are almost as hurt by the parent who did nothing to stop it as they are by the one who abused them.

It will probably take a psychotherapist to change your husband's behavior, but it's up to you to see that your children are safe with their father and everybody else.

Marguerite Kelly is on vacation. This column first appeared on July 23, 1992.

Questions? Write to Box 15310, Washington, D.C. 20003, or e-mail advice@margueritekelly.com.