DEAR ABBY: Every year, I throw a Christmas party for 25 or 30 people. What is the polite response when I'm asked by a prior attendee, whom I do not wish to invite, if I am throwing a party again this year?

This happened three times last year, and I don't know how to handle the question. I could never respond with a blunt, "Yes, but you're not invited." Nor would I be comfortable with the lie of "No." So I usually stammer some vague nonanswer about not even having my Christmas cards out yet.

My honest response would be, "I am -- but regrettably, I just can't invite everyone I would like to. Let's plan to get together after the holidays."

I don't want to cause the hurt feelings that being excluded would create, especially when it is someone whose company I enjoy. At the same time, though, I am blessed with a large circle of friends and acquaintances, and can invite only so many people.

How would you or your readers respond to a question like this that probably shouldn't have been asked in the first place? Or am I just being overly sensitive? -- POLITE HOST, SEATTLE

DEAR POLITE: You are not being overly sensitive -- you are simply a host who has trouble saying no. Your honest response is the best way to explain the situation.

DEAR ABBY: You recently printed a letter from a woman who is involved with an HIV-positive man. I tested positive seven years ago and am still as healthy as ever. To others in her situation I would say: Go ahead and live your lives. It would be sad to break off a promising relationship for fear of an illness that may never happen. However, at the same time, be wise and make a plan for what you'll do if he does get sick. This same advice applies to any mature couple.

I'd like to offer a list of suggestions that might be valuable to anyone who tests HIV-positive:

1. Make sure you have good health insurance. Get medical exams several times a year from a doctor who has experience with HIV. This is important so that potential infections can be nipped in the bud.

2. Reduce the stress in your life. Stress can weaken the immune system.

3. Don't waste energy feeling ashamed about HIV. It's just a particle of protein. Let family and friends know, by your example, that you're the same person you always were.

4. Learn as much as you can about HIV treatments. Many people with HIV never develop AIDS, and new medicines are helping people with AIDS live longer and better lives. You are your own best advocate.

5. Expect to experience periods of fear, sadness and anger. Talk about your feelings with someone you trust, and don't be afraid to ask for help. A support group of other people in your situation can be an excellent way to deal with feelings and share information. -- LIVING WELL IN KENNEBUNK, MAINE

DEAR LIVING WELL: I'm sure that many people will benefit from your sensible suggestions. Thank you for a helpful letter.

What teens need to know about sex, drugs, AIDS, and getting along with peers and parents is in "What Every Teen Should Know." To order, send a business-sized, 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. 61054-0447. (Postage is included.)

DEAR ABBY: I have been with my boyfriend for four months and recently lost my virginity to him. I am incredibly in love with him.

I would like to tell my mother about losing my virginity because I want to get on birth control pills, but I'm afraid of how she'll react.

My mom is very understanding and I can usually tell her anything, but I'm afraid that if I tell her this, she'll try to keep me from seeing my boyfriend. She likes him a lot and has always trusted us. Please help me. -- AFRAID SHE'LL END IT IN NEW JERSEY

DEAR AFRAID: Sex is a grown-up responsibility, and since you have taken the step, it is extremely important that you act with maturity. Your mother is your best friend, and although she may be disappointed, she will understand. Now that you are sexually active, it is essential that you practice birth control and learn what you need to know about sexually transmitted diseases that are rampant.

If your mother is as understanding as I think she is, she won't stop you from seeing your boyfriend.

DEAR ABBY: I work in a confined place with a woman whom I love. I am divorced and was very lonely until I started working with her. She treats me better than any other woman I have ever met. We have a special, non-sexual relationship.

She seems to be happily married and I can never hope to be with her other than at work, where we spend many hours together with little to do except talk to each other, entertain each other and -- well -- flirt. I know she enjoys my attentions, but I also know that sooner or later she'll tire of this and crash me hard.

I have been divorced for three years, and I doubt that any other woman would be willing to take on a divorced man who has weekend visitation with his daughters. I am attractive and intelligent, but very lonely, and my co-worker fills a big void. Without her friendship, I'd have little sunshine in my life.

How can I control my feelings and not be in love with another man's wife? How can I keep my job, interact with a beautiful co-worker and keep my heart in check without hurting her or getting hurt? Please answer soon. I can't afford counseling. -- IN LOVE WITH A PRINCESS

P.S. If any women respond to my letter, please give them my telephone number.

DEAR IN LOVE: Love? Face it, you are lonely. Your self-esteem is below ground level, and you are ATTRACTED to her. That's not love -- that's distraction from your misery.

If any women respond to your letter, I will tell them what I'm telling you: Mine is an ADVICE column, not the "Personals" page. The way to find a worthwhile, constructive individual is to go where worthwhile, constructive people go.

DEAR ABBY: On our daughter's 40th birthday, a simple bouquet was delivered to my husband and me with a card that read, "Thank you for having me, for caring for me, and for sharing all that I needed with me."

Abby, this has occurred every year since her seventh birthday when she presented us with a straggly bunch of wildflowers. The idea was her own.

There is nothing more precious than her yearly thank-you. I would love for those reading this to do the same, whatever their age. It's never too late to give this gift of appreciation that makes parents' hearts sing. Gratitude is ageless. -- MARY L., ROCHESTER, N.Y.

DEAR MARY: And thank YOU for reminding all who read this that expressing one's appreciation is in itself a priceless gift.

For everything you need to know about wedding planning, order "How to Have a Lovely Wedding." Send a business-sized, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Wedding Booklet, P.O. Box 447, Mount Morris, Ill. 61054-0447. (Postage is included.)

DEAR ABBY: On Wednesday, April 9, 1997, I sat on the edge of my father's bed and held his hand while he drew his last breath and quietly passed away after a brief, devastating battle with cancer. He was only 65, didn't drink or smoke, worked out on a regular basis, ate only fruits, vegetables, fish, bulgur, oatmeal and whole-grain bread. The doctors said he did everything right.

There were only two things that perhaps could have saved him -- regular physical examinations and prostate exams. My father disliked doctors (his mother died on the operating table when he was 12). However, a persistent backache drove him to the doctor in December of 1996. X-rays revealed spots in his lungs, which were found to be cancerous. His back pain was caused by the cancer eating away at his ribs until they crumbled and broke.

In February, it was discovered that cancer had also invaded his liver. These were all secondary cancers spread by a primary cancer, which was never found. The doctors suspect that the primary cancer started in his prostate. Due to the fact that his was a widespread and rapidly growing cancer, treatment consisted only of controlling the pain. It was too late for any hope of curing him. In fact, the doctors told him to consider each day his last.

My father was loved by everyone who knew him. He had a wickedly funny sense of humor, and was kind, warm and intelligent. He always assumed the best in everyone. His generosity included donating his body to a medical hospital for study. He was my best friend, and I miss him terribly. Now my mother is left alone in what should have been their retirement years. I'm mourning a series of sad "firsts" -- my birthday, then his birthday, then Father's Day without him.

Please, Abby, urge all dads to get regular checkups, including prostate exams. -- SUSAN HARWICK, SAVAGE, MINN.

DEAR SUSAN: There is no way I could do it as eloquently as you have, with your graphic letter. Susan, please accept my deepest sympathy on the loss of your beloved father. I hope that the details of his untimely death will spur other men to call their physicians and make appointments for annual physicals, which should include a prostate examination for any man over the age of 50. The physical should also include a breast examination -- women are not the only ones who get breast cancer. Insist, if necessary.

DEAR ABBY: I have a friend who believes himself to be quite intelligent. At every opportunity, he finishes sentences for anyone trying to speak. It seems as though he wants everyone to know that he has it "all figured out" ahead of time. It is annoying to have a great story ruined as he kicks in with the punch line (or a version of it) before the storyteller can finish.

If someone says, "Oh, you've heard it before," he will respond with, "Oh, no," and laugh, covering his face with his hands, feigning embarrassment for his "blunder." (In most instances, I believe he HAS heard the story before.)

Isn't this behavior rude? It is annoying to be constantly interrupted, or to have a good story ruined. How should I handle this? -- UPSTAGED IN OLYMPIA, WASH.

DEAR UPSTAGED: The next time it happens, you would be within your rights to tell him emphatically just how you feel about being interrupted while he finishes the story for you. If more people spoke up, he might shape up and shut up.

THOUGHTS AT NIGHT: "It often happens that I wake up at night and begin to think of a serious problem, and decide that I must tell the pope about it. Then I wake up completely and remember that I AM the pope." (Pope John XXIII, quoted in Forbes magazine)

What teens need to know about sex, drugs, AIDS, and getting along with peers and parents is in "What Every Teen Should Know." To order, send a business-sized, 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. 61054-0447. (Postage is included.)