I guess I don't understand why the "kids, we're poly" topic had to come up at all. But then, my kids are only 2 & 4. I just don't see how the fact I'm poly, or bi, or anything else pertaining to my romantic and sexual life is any of my kids business. When my boyfriend comes over, it's no different than when my other friends come over. I don't behave in any way that should raise a red flag from even an older child -- but then, I also don't behave inappropriately with my husband in front of the kids.
I agree with the posters saying that it is probably way more information than your kids wanted about their parents' personal lives. I hope your family can sort it out so things aren't so dramatic in your home and your kids can feel better about things.
"This, too, is sacred."
I am my own primary.