Dear Carolyn:

I have a reunion coming up this summer in New York. At college I shared a dorm room with a close friend from high school. She was engaged our junior year but was unsure about her decision. She cheated on her fiance -- which I, being stubbornly moral, decided wasn't right. I told her fiance and they broke up. She NEVER spoke to me again.

I know it wasn't my business to tell him, but, having divorced parents, I was trying to prevent them from making a mistake. I heard she is now married to a different guy, and I hope she is happy. I want to say hi at the reunion, but I'm afraid she might be, like, "Why are you talking to me?"

Should I tell her I'm sorry but that I thought I was helping, or should I forget about the past -- even though I'm sure she remembers?

Virginia

Your friend may have a stubborn moral objection to rats, so I wouldn't use the I'm-sorry-but-I-was-just-being-superior tack when you make your apologies.

And apologize you must, no buts. Practice in front of a mirror if you have to: "It was none of my business to tell him, and I'm sorry." Period. Mouth closed. Because it wasn't your business, except as an issue between you and your friend directly. Your pain, I'm sure, was real and your moral outrage justified, but you delivered this self-righteous package to the wrong address.

When you're ready to admit this error -- without editorial comment -- call her. Don't wait for the reunion. Your mutual friends will be unspeakably grateful to you for duking this out before you ruin their party, for one thing. And it'll show that your vision has improved when it comes to spotting the high road.

Dear Carolyn:

I worked in a small office that's had a rash of departures due to temperamental management and back-stabbing among employees. There are still very hard feelings. I have been cordial with everyone -- although I finally left a few weeks ago.

A group of my former co-workers is giving my fiancee and me an engagement party, and I know some of the hosts wouldn't be crazy about our inviting some of the people we'd like to include. Should we invite everyone we want, or give fair notice that we're inviting people they'd just as soon never speak to again?

Tennessee

Or . . .

Come on, you can say it: "Or do we accept that the Hatfields are hosting, and so we might have to exclude the McCoys?"

"Peace on Earth" is a brilliant concept; civility, maturity and tolerance are no less ducky themselves. But this party is being thrown for you, not by you, so your order-giving, notice-sending reach extends roughly to the edge of your shirt.

If the hosts said explicitly that you're free to invite whomever you choose, then you have some control over the guest list. But the gracious way to wield it is to ask the Hatfields how they would like you to handle the delicate matter of the McCoys. If they balk at inviting the enemy, make your case (gently) for charity, forgiveness and apple pie.

But first, a question of my own. In the office meltdown, who was at fault? While you're a champ for staying civil, you forfeit champhood if you remain friends with back-stabbers, particularly if your other friends were victims. If the lines are too blurred, go with tactful negotiating. If the lines are clear, dust off your principles and take a stand: Friends welcome, back-stabbers not.

If If If. I am weary of typing "if."

Dear Carolyn:

I'm a single, professional, well-employed guy, not self-absorbed. I commute by subway, and every day I see interesting-looking women. What do you think the average woman-on-the-street's reaction is to being addressed by a stranger while waiting for the train, getting lunch, whatever?

Washington

I think women want to think it's refreshing to be addressed by strangers -- until they feel totally unnerved when addressed by a stranger. Or worse, when hit on by one. Guys on trains, you see, don't have context. No friends, no co-workers, no sweet yellow Labs -- none of the usual "references" we use to screen pity cases and serial killers. (Yes, we fear both equally.)

But that doesn't rule out spry commuter banter. Clean-cut and good-looking buy you some leeway, sick as that is. Plus, I think we're all desperate for some sidewalk civility. When fate hands you an opening -- a too-packed train, a long delay -- you can whip out a quip with minimal risk of a restraining order (especially if it's actually funny). Just don't push it -- and if you tank, change cars at the next stop.

Write to Tell Me About It, Style Plus, 1150 15th St. NW, Washington, D.C. 20071, or tellme@washpost.com, and join Carolyn's live discussion at noon today or at 8 p.m. Monday on The Post's Web site, www.washingtonpost.com