AITA for leaving my cousin's wedding early after I found out where I was seated?

I (27F) went to my cousin's wedding this weekend. We grew up pretty close, so I was excited to be there.
When I got to the reception, I found out I'd been seated at a table with people I didn't know at all. It was basically the "overflow" table friends of the groom's parents, a couple of distant relatives, and one random plus-one. Meanwhile, all of my siblings and cousins were sitting together at another table.
At first I figured it was a mistake, but when I asked my cousin about it, she said she did it on purpose because "you're easy to talk to" and thought I'd help the quieter guests feel comfortable. She also said the family table was already full.
I didn't make a scene or anything. I just went back to my seat and tried to make the best of it. But honestly, it felt kind of crappy watching everyone else in my family laughing together while I spent most of dinner making small talk with strangers.
After dinner and the speeches, I congratulated the couple, said goodbye to a few relatives, and left instead of staying for dancing.
The next day my cousin texted me saying she noticed I'd left early and that it hurt her feelings. I explained why, and she said I was acting childish over "a seating chart" and that weddings aren't about where you sit.
Now a few family members are saying I should've just stayed because it was one night and the day wasn't about me. I get that, but I also felt like I was treated more like a host than a guest.
AITA for leaving early?

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u/green-wine — 11 hours ago