Ok, excuse my fuming-ness - I've had this recounted to me by an upset 5yr old!
ExH and his new GF took DD out for a day, he hasn't seen her in a few months and GF hadn't met DD before, but they wanted to take her for a day to a local attraction. DD was excited to go. This I have no problem with.
Apparently, at some point during the day DD had been playing and another person, innocently, said something along the lines of "you look like you're having a nice day out with mommy and daddy" - DD apparently said "that's not my mommy" and ExH stepped in and said to the person that it was, and later said to DD that his GF was "her other mommy", said that she should call her mommy because she was the same as her mommy.
DD was quiet when they dropped her off which I expected as she would be tired, but later recounted the story to me and got upset, I think she was confused by the whole thing.
My inner tiger mother wants to rip ExH's head, just for confusing and upsetting DD, but I wanted to check first whether I was being silly!