Q. My brother is angry with me because I am best friends with his now ex-wife, Samantha. He expects me to abandon a 12-year friendship because they broke up. I haven’t taken sides. And, I’m not so sure they won’t get back together. I’m just not willing to walk away from my best friend and my children’s favorite aunt! My kids are only 3 and 5! What’s good ex-etiquette?

A. And, you have now described the great Ex-etiquette Paradox.
Our exes are not just our exes. They are also our children’s grandparent, aunt, uncle, cousin, godparent — the list goes on and on.

Little ones need to know on which grownups they can depend. If Auntie was a trusted adult, they wouldn’t understand why they can no longer see her just because she is no longer married to their uncle. Very young children don’t understand that Aunt Samantha is Daddy’s sister. That understanding comes a little later than 3 and 5.

That said, it’s understandable that your brother expects allegiance, but this may be impractical in your situation. There are too many relationships intertwined with one another. So, in cases such as these, strong boundaries are necessary.

That means establish rules of engagement with your brother and your best friend. For example, make sure no one badmouths your brother or your sister-in-law in front of any of the kids — or to anyone else, for that matter.

Also friends tell each other intimacies. I’m not saying stop that, because people often work out their problems venting to their friends or family. But beware of where the kids are when your sister-in-law or brother are crying the blues and you are trying to comfort them.

It may be best if you want to stay friends with your sister-in-law and your brother to simply put a boundary in place that says you love them both but will not be available to discuss the specifics of their breakup. If you can do it, you can keep your brother and your best friend’s trust intact. That’s good ex-etiquette.

Dr. Jann Blackstone is a child custody mediator and the author of “The Bonus Family Handbook: The Definitive Guide to Co-parenting and Creating Stronger Families.” www.bonusfamilies.com/Tribune News Service