DEAR ABBY: I walked into my dorm room and heard my roommate having sex in the bathroom. I promptly called my girlfriend to ask if she wanted to meet me. No sooner had I entered her number than I heard my girlfriend’s ring tone coming from our bathroom. It was her.

I clicked off, left the room and stayed at a friend’s for the night. Please tell me, did I do the right thing and what do I do now? — BETRAYED IN TORONTO

DEAR BETRAYED: I’m sorry you walked out. You should have ordered a pizza and invited some (true) friends over so they could be there when the two of them emerged.

Here’s what to do now: Tell your girlfriend the romance is history, and start looking for a roommate with enough character and intellect that he understands boundaries.

DEAR ABBY: I am shocked at what my young children tell me they have overheard while other “carpool moms” chat on their cell phones as they ferry children back and forth to school. Cell phones have opened up a whole new adult world to children.

My children have heard mothers bad-mouth teachers, other parents and even their classmates. They have also had to listen to adult arguments that were none of their business. In one extreme case, my son had to endure hearing the carpool mom relay the circumstances of his own father’s sudden death! Can you imagine how painful that was?

Parents, please remember that little children have big ears and listen to everything you say! — HANG IT UP IN COLUMBIA, S.C.

DEAR HANG IT UP: Thank you for writing. As tempted as I am to use your letter as yet another reason to discourage the use of cell phones and other electronic devices while driving, no state can legislate that its citizens use common sense. Too bad.

DEAR ABBY: Please warn all those poor trusting souls out there never to give out their passwords — ever!

I work in an office with about 20 people, mostly middle-aged women, many of whom are going through divorces. I have noticed a disturbing trend — cyberstalking. Several of the women use passwords provided to them in the past, when the relationships were good, to access personal data.

One woman accesses her husband’s bank account so they can all have a good laugh at how he’s struggling financially. Another has her ex’s e-mail and Facebook passwords and delights in telling everyone about the angry messages being left by the ex’s new girlfriend. The latest is the use of an ex-husband’s password to spy on his online dating account.

Tell your readers out there to safeguard their passwords. Don’t give them out no matter how much they trust someone. But if they do, when the relationship ends, change each and every one — no matter how inconsequential. — SICK TO MY STOMACH IN CONNECTICUT

DEAR SICK: I’m sure your letter will cause readers of both sexes to do a double take. No one can ever be too careful with personal information. Revealing a password is like giving someone the keys to your house, your safe- deposit box and your diary.

Dear Abby is written by Abigail Van Buren, also known as Jeanne Phillips, and was founded by her mother, Pauline Phillips. Write Dear Abby at www.DearAbby.com or P.O. Box 69440, Los Angeles, CA 90069.