AITJ for telling my cousin I wasn’t comfortable putting her name on something she didn’t help with?

My cousin and I are both involved in planning family events. A few months ago, my aunt asked me to organize a small celebration for my grandparents.
I handled most of it myself finding the venue, contacting the caterer, arranging the decorations, and keeping track of the budget. My cousin helped me once by suggesting a few decoration ideas which I appreciated.
A few days before the event, she asked me to put both our names on the thank you card as the people who organized everything.
I told her I didn’t think that would be fair because I had handled most of the actual planning, I also said I was happy to mention that she had helped with the decorations.
She became upset and said I was being petty over a name on a card, She reminded me that we’re family and that I shouldn’t care about getting credit.
I told her I wasn’t trying to take anything away from her. I just didn’t want to claim that we had done something equally when we hadn’t.
She eventually said I had made her feel unappreciated and decided not to attend the event.
The event went well, and afterward several relatives thanked me for organizing everything. I didn’t mention the disagreement to anyone.
My cousin later told me that I embarrassed her by refusing to include her name and that I cared more about recognition than family.
I honestly don’t feel like I was asking for recognition, I just wanted the description to be accurate.
AITJ?