Parenting differences

JJ and I have been doing a bit better, so something that happened today felt jarringly bad. We were on our way to Alexandria for a weekend visit, and the trip was off to a good start. After several years of conflict over traveling there, with JJ not wanting to come on most trips there with me, he actually agreed to go without issue, and seemed into the idea. So all was well the first part of the trip. But then we stopped at Chesapeake House for lunch. It was pretty crowded and the lines were long. After taking the kids to the bathrooms, we met up by the lunch lines. JJ told me he had already ordered a pizza at Pizza Hut. I asked Merryn what she wanted and she said "chicken and fries." I waited in the KFC line and got her some chicken tenders. Then I got in the Wendy's line and got her fries and a salad for myself. Merryn was with me the whole time. When we got out of the line, Merryn said, "did you get me my burger?" I said, "no, you asked for chicken." She started crying and said, "I changed my mind! I wanted a burger!" I said, "you didn't say that. I didn't know that. Now we're out of the line." We went to sit down and she was carrying on about how she didn't want the chicken and she wouldn't eat it. She demanded that I go get her a burger. She  was demanding that I get her fries out of the fry box for her even though it was right in front of her. Lots of drama. I told her, "Merryn, I don't like this behavior. I don't like you screaming at me and demanding things from me. I bought you the chicken that you asked for so that's going to be your lunch today." She was having a full on melt-down, shouting at me, "Mommy, YOU ARE NOT NICE! Bad Mommy!" Meanwhile JJ was buying milk for James. As he came back to the table, Merryn said, "I am going to tell Daddy that you are not nice!" People at other tables were turning to look at us. When JJ came back, Merryn said, "Daddy, I wanted a hamburger and Mommy won't buy it!" JJ started to walk towards the Wendy's line. I said, "JJ, wait. I actually don't want you to go buy her the burger. She asked me for chicken, and now she is screaming at me about it. I want her to understand we already got her a nice lunch and paid money for it..." He was barely listening, then he dismissively said, "it's just a hamburger," and walked over to the Wendy's line. I felt I had just gotten hit with a sucker punch. I felt completely undermined in front of our kids. I was too mad to even talk. While he waited for the burger, which took more than 10 minutes, Merryn was still telling me that I was a bad Mommy the whole time. When JJ came back, I said, "you undermined me in front of our kids. I wanted Merryn to understand the value of a dollar and to understand she can't just cry and whine to get what she wants. Did you get to do that as a kid, just demand things from your parents until you got whatever you wanted? Her behavior was kind of bratty and I don't want that!" He said, "it's just a burger. You can eat the chicken." I said, "I don't want to eat the chicken! And it's not about the chicken or burger, it's about the message you just gave her, and the message you gave me. You just told her that if she doesn't get what she wants from me, she can just come to you. And you totally disregarded my opinion in front of our kids and disrespected me! What message do you think you just sent them, and me?" He started snickering at me like it was the stupidest thing he ever heard. I said,"you asshole." I was so mad I didn't even want to sit at the table with him. I took James for a walk outside. And now the test of the day has passed and we have barely spoken to each other.