I have knowledge of someone's affairs. What do I do about it?

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Dear Prudie,
I am 30 and recently moved to be near my parents, who have been married for 35 years. My father has a long history of infidelity, which my mother thinks is over. Almost a decade ago, she found out he was still having an affair with the woman who had worked for him in the 1980s. He had moved her across the country and gotten her an apartment near our house. My mom left my father for a couple of years, but last year they got back together, and they've moved to a remote part of the country and started over. My father confessed to me last week that he was still seeing his longtime girlfriend. He tells my mother he's taking a business trip or a "guy's weekend." He has no intention of telling my mother about her, but plans to see her for the rest of his life. He wants me to keep quiet about it, but he's sloppy about his affair to me (accidentally sends me text messages meant for her, gives me a book to read with an inscription from her on the inside cover, etc). I don't want to tell my mother—I really believe she thinks the affair is over. I don't want to be involved in the details of my parents' marriage, but my father shared this information with me. Is keeping his affair a secret from my mom deceptive? How do I handle him leading two lives, one of which is hurtful to my mother, whom I love dearly and don't want to get hurt?

—In on the Secret

Dear In,
Now we know that moving a committed philanderer to the backwoods will not put his compulsion to cheat into hibernation. This soap opera has run longer than The Young and the Restless, and given your father's sloppiness (could he possibly be losing it?), it sounds as if it's good for a few more explosive turns. You have been put in a terrible position, but you are not obligated to move the plot along. You must make clear to your father that you don't want to hear anything about his girlfriend, ever again—and that includes misdelivered text messages. Your parents' marriage has been decades of revelations, tears, regrets, and false promises. If your mother decided to give it yet another go, she can't have gone in with many illusions. When she eventually finds out—and it sounds as if your father's trying to get that penciled in—she might ask if you knew. Be honest that your father spoke of it once, and you told him that you didn't want to be involved in their intimate affairs. Since you say you want some distance from their relationship, why did you move to the back 40 to be near them? Maybe it would make more sense for you to be closer to civilization when your mother does discover yet again that your father's leading a double life.

—Prudie

Dear Prudence,
Two of my best friends are likely to become engaged this year. I played Cupid for them a few years ago and have watched with joy as their relationship blossomed. I'm a bit closer to the bride-to-be, and a few months ago, she dropped a bombshell on me. She confessed that she's cheated on her boyfriend, my friend, several times—once with a married father. When I insisted that she tell her significant other, she balked, saying she "didn't want to lose him." I love my girlfriend and want her to be happy, but I also respect this man and think it would be unfair for him to be ignorant. She assures me her cheating ways are in the past. Would I be a better friend to keep this to myself, or tell him knowing that I might lose a friendship?

—Worried Cupid

Dear Cupid,
Speaking of The Young and the Restless, you have a chance to stop a marriage that's going to play out like the one described above. Certainly it's easier, and emotionally safer, for you to conclude that it's none of your business, everyone involved is an adult, and you should do nothing. But let's say the situation were reversed, and your girlfriend knew that your boyfriend had cheated on you multiple times during your courtship—wouldn't you want to know? Surely, if after the wedding, and after the baby, he shows up on your doorstep one night in tears saying he's found out his wife is cheating on him, you'd kick yourself for not having told him when he had a chance to decide if he wanted to take this risk with his life. Although you may lose both friendships, I think you need to let the guy know what's going on. The fairest thing for your girlfriend would be to give her a warning that you can't live with your knowledge, especially since you feel responsible for their relationship, so that she can have a chance to divulge this herself.

—Prudie

Dear Prudence,
There are two women in my yoga class who snicker and whisper to one another before, after, and sometimes during class. One day, I overheard them in the locker room and realized that some of the mean comments they were making were about me. They were pointed, critical, catty comments about the way I wear my hair in class—I wear pigtails and they called them "her sad little pigtails." I initially just shrugged it off. The next week, I walked into class ahead of them, and one whispered in a rather cruel tone, "She just always has be the first one in." The reason I go to yoga is to achieve a level of peace and focus, and these gossipy women are ruining it for me. I even said, "Hello" to one of them in an attempt to defuse the situation and got a very blunt, unfriendly, "Hello" in return. I started attending class on different days, but they've started attending the classes that I've switched to. Do I confront them? Kill them with kindness? Ignore them completely? I feel like I'm back in high school every time I go to yoga class! Yoga is the last place I want to feel any kind of negativity, let alone project it onto anyone else, but just knowing that these women like to make fun of me for no reason puts my defenses up.