He said, "So I hear you and your wife have an open marriage."

Pretty common for a WS to make up all sorts of "cover stories" if anyone confronts them... No telling how many WS tell their affair partner that they are either divorced, or going through a divorce, and then go home to their spouse and be all lovey-dovey...

I wouldn't worry about it too much... unless the investigating officer contacts you again and asks for more names from people relating back to her OCS days at Ft. Benning.

You're correct in this would just muddy the waters for the current investigation, and to be honest, they will most likely only be concerned with the time that OM got to Ft. Sill and your W got to Ft. Huachuca...

Semper Fi,