(Nick Galifianakis/for The Washington Post)
Advice columnist

Hi, Carolyn: My sister and I recently became aware that our brother, married for 12 years — we thought happily — with two young kids, is leaving his wife after having an affair for months. He's moving in with the other woman and has declared they are "in love" (gag). We are still reeling from this news.

My brother has told our parents about the divorce but has been vague as to the reasons.

Consequently, my parents believe the marriage may still be salvageable and are dead-set on helping them through this "rough patch."

I hate the position this has put my sister and me in whenever we talk to our parents — having to act as though we don't know what we know — but I also don't feel it's our place to level this devastating news to them. My soon-to-be-former sister-in-law believes my brother won't tell, and my sister has even questioned whether they need to know at all. She's concerned about our parents' health.

To me, that feels as though we're babying them. They are elderly and have some health issues but are not feeble or weak-minded. Not telling them feels dishonest and like a betrayal.

Should I give my brother a "tell mom and dad by X date or I will" ultimatum? Or just stay out of it?

— Stuck in the Middle

Stuck in the Middle: It’s not your news to tell, no.

But you’re only “in the middle” because it’s also not your news actively to withhold.

It is a well-meaning irony that trying to do the right thing is why you and your sister, and the estranged wife, now face these wrong-feeling choices, calculating who says/knows/withholds/deserves what.

A much simpler right choice preempts all such calculations:

Don’t cover for anyone.

You can decide that upfront as a policy, with anyone, about anyone, for anyone. From there, as necessary, you’d need only to state your policy on the spot to anyone who asks you to break it.

With your brother, it would have looked like this, once you learned of his intentions: “That’s your call, but I won’t cover for you.”

If he never actually stated his plans to you — if you just found out through the family back channels that your brother was playing down key facts — then you wouldn’t even have to declare yourself to anyone. You’d just apply your cover-for-nobody policy through honest participation in whatever conversations come up organically.

There’s room for abuse here, so I’ll elaborate: This doesn’t mean you blab your brother’s business everywhere. Discretion and privacy still matter. This is just about rejecting dishonesty, and refusing to abet the telling of self-serving fictions at someone else’s expense.

“Having to act” is abetting. You know what you know. So live and converse and respond as someone who knows.

Any pain this causes your brother is the pain he created himself. It’s not your job to guarantee he feels its full force, but it’s also not your job to buffer him from it, either. This erases the middle completely.

If you did agree to keep his secrets, then you owe him notice of your policy change. “I feel like I’m lying to Mom and Dad,” you can say. “So, new plan: I won’t volunteer anything, but I won’t cover, either. The rest is up to you.” And rightly so.

Write to Carolyn Hax at tellme@washpost.com. Get her column delivered to your inbox each morning at wapo.st/haxpost.