AITA for leaving my step sister's wedding reception where I was supposed to be taking pictures?

I am a professional photographer. Mostly industrial photography for businesses and such. I do other types for myself and as art. I love taking pictures of the old architecture in my city and of the surprising wildlife in it.

My mom asked if I would be willing to take pictures for my step sisters wedding to help them save money. She asked me to do it as a gift. She knows that Tina hates me and I pretty much reciprocate. I decided to be the bigger person and agreed.

I was there for the makeup and the wedding party getting dressed, I took a ton of pictures bat the wedding. I prepared a checklist of all the different formals she wanted and made sure I got them all. I did my absolute best.

When I got to the reception there was no place for me to sit. I had gotten there right away so I could get pictures of the wedding party arriving and all that. The wedding party had stopped to use the bathroom and get freshened up.

I called my mom to find out where I was meant to sit and eat and stuff. She talked to Tina and called me back. She was upset and I could tell. She said that Tina thought since I was working and not a guest she didn't have to have a seat and food for me.

I thanked my mom for the information and left.

I took my boyfriend who was my assistant that day and we went out for dinner my treat. We had been on the go for eight hours by then.

I turned off my phone. We had a nice night out and we saw the new Mad Max movie.

Sunday morning I turned on my phone. It was full of messages asking where I went. Then demanding I come take pictures. Then cursing me out.

I called my mom to see what was up. She said that Tina was very upset that I left and that all her reception pictures were going to be from cell phone cameras. She said I should have just gone to get a quick bite at McDonald's and then come back.

I told her that I felt terrible and would of course give a full refund. I also said that this was the last straw and that I did not want to hear shit when I did not invite Tina to my wedding next year.

Tina obviously thinks I'm an asshole and my mom thinks I should have kept the peace. I am just going to drop off a thumb drive with all the pictures band wash my hands of this. No editing. No nothing.