[libs_kma]

"--happened to a half-brother and sister in western South Dakota some years ago

--they tumbled to the fact at a family gathering where high school prom pictures were looked over--"

Can you imagine what you would feel as you came to the realization?

It would be too much to take in all at one time. And with your whole family there while you found out?

And both sides of your family at that (well, "both" and the same)!!

[rellimpank]

—last I knew they were still married—(unbelievably)—

[WoofDog123]

“It would be too much to take in all at one time. And with your whole family there while you found out?”

That is the big issue - finding out privately would allow some leeway in how to address it. Family present would just be a nightmare.