DEAR ABBY: Once again, you are receiving a letter from someone who never dreamed she would be writing to you for advice. Actually, I don't know if I want advice, or just need to get my feelings out. (I'm too ashamed to talk to any friends or family.)

I have been married for seven years to a wonderful man and I love him dearly. He has an 8-year-old daughter from a previous marriage. The problem is, I can't bring myself to "love" this child. I can't stand to be around her. I've always felt this way, but it has become worse since I had my own daughter 2 1/2 years ago.

My stepdaughter (I'll call her Mary) is with us every other weekend and on holidays. When Mary comes to stay, I get depressed because I feel I have to pretend to like her -- I don't hate her, and I would never hurt her. In fact, when she needs discipline, I bite my lip to keep from saying anything.

Mary has a sassy mouth and can be very rude to adults. My husband is aware of my feelings for her, but he doesn't know how deep they are. I truly love my own daughter, and when my husband walks in on Fridays with Mary, I cringe; when he leaves with her on Sunday, I let out a sigh of relief.

I hope one day things will get better, but right now, I can't seem to get over my feelings. -- ASHAMED

DEAR ASHAMED: Congratulations -- you have already identified your problem, are properly contrite and want to resolve it. We all have people in our lives we cannot "love" or even like, so don't be ashamed.

You need to find out why you have such hostile feelings toward this 8-year-old child. Perhaps it has something to do with her being the daughter of your husband's former wife.

You could also be reacting to Mary's negative feelings toward you. After all, you are the woman who replaced her mother. And it's also possible that Mary's mother may have influenced her.

Please consider a family therapist. Your problem may be solved once you understand why you and your stepdaughter feel the way you do.

DEAR ABBY: My husband and I were invited to a dinner party at the home of a very high-class, prominent society leader, who has a reputation for entertaining beautifully.

My husband's widowed sister came to town unexpectedly, so I telephoned my hostess and asked if I could bring our houseguest.

She asked, "Is your houseguest a male or female?"

I said, "She is my husband's widowed sister."

Abby, would you believe this so-called high-class society lady replied, "Oh, dear, that's too bad; we already have three extra women -- if you could bring a man, I would be delighted, but we don't need any more women."

Have you ever heard of anything to top this? -- SPEECHLESS IN LA JOLLA

DEAR SPEECHLESS: Yes. It actually happened to a friend of mine some years ago. When she was told an extra man would be welcome, but they couldn't accommodate an extra woman, she replied, "Oh, I didn't know we were going to mate at the table." (Thank you, Mickey Ziffren.)

Most teen-agers do not know the facts about drugs, AIDS, and how to prevent unwanted pregnancy. It's all in Abby's updated, expanded booklet, "What Every Teen Should Know." To order, send a business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Teen Booklet, P.O. Box 447, Mount Morris, Ill. 61054. (Postage is included.)

DEAR ABBY: I can certainly sympathize with "Pressured in Pennsylvania" who wanted a "no-child" wedding. All of the invitations to my daughter's wedding last month were worded in the correct way and addressed to "Mr. and Mrs." We assumed that by not including "and family," we would have no trouble. Wrong!

Friends whom we had not seen in a number of years, and would have welcomed with open arms, announced that they were coming 500 miles to the wedding and bringing their married daughter (who was invited) and her three small children (who were definitely not invited!). It fell to me to telephone long-distance and tell them that the children were not included in the invitation. They said they had never heard of such a thing, and if the children weren't welcome, they wouldn't be coming either. I stood my ground and said I was sorry, but that's the way it was. They never came.

Also, my daughter and I spent an entire weekend calling people who had failed to RSVP. A number of them told us they thought that if they were not planning to attend, they did not need to respond. (What did they think the stamp on the return envelope was for?) Several accepted but never showed up.

Abby, I think it's time to change the rules. Tacky or not, if I ever have to do this again, I will state on the invitations:

"Sorry, adults only.

"Please respond with a yes or no. A stamped envelope is included for your convenience."

And finally, the ultimate in tacky: "No-shows will be billed for the amount charged per person, by the caterer." (In our case, it was $30 per head, and we were out several hundred dollars and a lot of food went to waste because of those thoughtless people.)

Thank you for listening because I really needed to get this off my chest! If you print this, please do not use my name. -- OUTRAGED IN OREGON

DEAR OUTRAGED: My mail over the years indicates that many people do not understand what RSVP means. Perhaps the following would be preferable: "Please respond with a 'YES, we will be there' or, 'NO, we will not attend.' A stamped envelope is enclosed for your convenience."

P.S. Many people have written to say, "We thought it wasn't necessary to respond because we cannot attend." Others in equal numbers wrote to say, "We didn't respond because we will be there."

DEAR ABBY: We would like to pass along a family tradition we started some years ago. A few days after each Christmas and birthday, we go through our daughter Kristin's toys. With her help, we decide which toys she doesn't play with -- or has outgrown -- and would like to give to less fortunate children.

In addition to the obvious benefit of children getting toys they might not otherwise receive, it teaches our own child the joy of sharing.

So instead of selling those old but good-as-new toys your children have outgrown -- or boxing them up to store in the back of your closet or attic -- give them to your local charity. After all, isn't the joy of giving worth far more than a couple of bucks made from a garage sale? -- THE MC ALEENEN FAMILY, CHARLESTON AFB, S.C.

DEAR MC ALEENEN FAMILY: Hooray for you. May each successive holiday season by happier than the previous one. You deserve it.

Abby's family recipes are included in her cookbooklet. Send a long, 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 writing this as a follow-up to the letter I wrote you in June about my 13-year-old daughter. (I told you she was getting dangerously close to the boyfriend she had been seeing morning, noon and night.)

I took your advice and spoke to her about sex. I purchased at the local drugstore several forms of birth control (condoms, contraceptive sponge and vaginal suppositories). I also bought something called a "teen pack," which contained several trial-size items introducing young females to such things as tampons, mini-pads, maxi-pads, shaving lotion and razors for shaving legs. When I got home, I invited my daughter to join me at the kitchen table. My husband was working late that night, so it was a perfect opportunity for girl talk.

I lined up the contraceptive devices on the table. My daughter was a bit curious. I gave her the teen pack, telling her that all the items in that package were things that we had discussed. Then I pointed to the other items on the table and said they were items that we needed to talk about.

I carefully explained to her that now that she had become a young woman having a monthly period, she could become pregnant if she had sex. I then told her that I was in no way condoning sex in someone as young as she, but that I wanted her to be informed. I then took each product and explained how it was used, and showed her the directions and how to check the expiration date on the product. After that, I opened each package and let her touch the device, examine it and ask questions.

I made sure she was aware that even if you are on the birth control pill, that still did not stop sexually transmitted diseases such as AIDS. I told her that safe sex with condoms could not completely guarantee the prevention of pregnancy or disease, but that the only way to ensure not getting pregnant or a sexually transmitted disease was not to have sex.

I then took the remaining products and placed them in a box in her bathroom closet. I told her I would not check the box, but if she ever felt a need to experiment, that they would be there. I stressed to her to always feel that she could come to me before making any decisions that could change her life forever.

And, I made some important points to her that truly hit home: I pointed out that she was too young to obtain a driver's license, too young to drink, too young to get a job, and too young to be responsible for the life of another human being. I reminded her that if she were to have a child, her education and social life would cease until such time that she could afford a baby sitter to resume her studies and social activities.

I realize this letter is lengthy, but I wanted you to know how I dealt with this issue. My daughter, after our talk, has been a different person!

I trust my daughter, and your advice was a big help in dealing with a very difficult situation. I realize that I have a long way to go in completing the journey through her teen years, but I feel that we, as a family, will survive.

I am truly grateful, Abby. Thank you. -- NORTH DAKOTA MOM

DEAR MOM: Every daughter should have a mother like you.

By popular request, Abby shares more of her favorite prize-winning, easy-to-prepare recipes. To order, send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: More Favorite Recipes by Dear Abby, P.O. Box 447, Mount Morris, Ill. 61054. (Postage is included.)