You have to keep conversation topics separated. Direct conversations to stay focused on the topic at hand.

+ R and M talks stay on topic

+ kid talk is about the kid

+ financial talk stays on financials

You got caught following her into conversation that did not relate to transportation costs.

Your Ds hometown is irrelevant. Fact is, you are in austin, W is in DFW. That's where the conversation should have been stopped. You mentioned travel cost not in decree, she didn't like the idea, you asked her to discuss with her lawyer. That's it.

That's OK. What happened, happened. You have to be less hard on yourself. Let what she said roll off your back as best you can. Learn to be more focused on the information that needs to be passed between the two of you at any given time. Be better next time. :-)