Apparently your DH panicked and felt like she was the only one who would know the answer to his question. It most likely wasn't that he was trying to disrespect you or your relationship or sneak off with her...it's more likely that he just didn't know what else to do or knew that she had the answer and was lazy.

I have fallen into this trap with my ex. She handled the business side to our relationship. She really handled everything. She told me what I was eating, where we were going and when. She paid the bills, knew when the bills were due, etc., etc., etc. When we broke up, the lights were cut off twice because I had no idea what was going on and I'd text her trying to find an answer because it was easier. She railed me and told me I needed to figure it out - she was right. I did eventually and moved on. She took my dog for 5 months, finally gave him back because she & her new SO didn't want to "deal" with him - he was a completely different dog. He still has social issues that I never had to deal with, he also came back with stomach issues I have to deal with - I sometimes still want to ask wth she did with/to him when she had him, but I know that I need to just pretend I got him from the pound and I have no way of knowing his history - I just need to relearn my dog.

Your DH made a mistake - he does need to be more mindful of you and the relationship and what messages he could be sending to the ex, others and you. Be patient, we men don't always learn quickly.