AITA for 'choosing an event' over Family?

I (29F) have a small business with a good friend of mine (29F), We'll call her Jay. Some of my family wasn't happy when I started this business with her but I figured it would be a good way to sell some of the copious amounts of artsy things I make (Jay is also very crafty but part of my family doesn't like her, this will be important later).

So, let's go back to last year for some context. Jay was my MOH and she isn't afraid to speak her mind and put her foot down, I am a people pleaser and have been working on that. At my wedding, since it was a day before my sister's, "Kendra" (36F) birthday, Jay approached Kendra and told her not to start anything because the day wasn't about her, Kendra found this incredibly rude. Jay then approached my mother, and told her not to speak to my father (my parents are divorced, bad bad divorce), so to avoid drama. My mom found it rude too. They both told me they never wanted to speak to Jay again until she apologized. Jay refuses to. My mom and Kendra didn't like Jay before this but that was the final nail in the coffin. Since then, they've been trying to get me to stop my small business with Jay.

Kendra recently started a small business herself and has been trying to get me to help with her business even though I've told her, I can help with some advice but she'll have to do a lot on her own since I'm focusing on my business. She did not like this answer.

Anyway, one of my wedding gifts was a one night stay at a Hilton from his boss, downside, its only valid at the Hilton thats literally 5 minutes from our house. So, we decided to give it to my mom to use since she lives two and a half hours away. Originally, she was going to come down the day after Christmas but a blizzard kept her at home. Then, we planned for a weekend in January, but she couldn't get off of work.

So, we planned for the first weekend of March. Here's where the problem came in. Jay called me one night at work with exciting news, a friend of ours got extra tables at a Trading Card Game Convention and offered a table to us because they gave her two too many. I forgot about my mom coming down so I said yes. We'd been trying to get a table at this convention for the last two years since we make a lot of Pokémon themed products. The next day, my mom messaged me and she said she was excited for the first weekend of March. I apologized and said I'd be out of town because I completely forgot about her visit and asked if we could reschedule. She said she was disappointed but she understood since it was an event we were trying for years. So I figured everything was okay and we rescheduled for later in March.

That was until I got a phone call from Kendra today. She was livid and screamed at me for being heartless for choosing this event over family. Apparently, my mom called her upset yesterday about how hurt she is over this whole thing and she thinks I'm choosing my small business over her family. I felt bad up until my sister slipped out some information that I didn't know. She wanted our mom down here because she had a vendor event in her town that weekend. Almost every time I had an event near our mom, Kendra had to come up with a reason why our mom had to go to her instead. My mom has also been trying to convince me to drop my small business to help my sister with hers and thought that weekend would be the perfect opportunity.

Why? Because my sister needed a babysitter and why should I deal with my small business when I should help my family and watch her kids for her.

I talked to Jay and she agreed it was an asshole move on their part. I also talked to our brother, John (34M), about it and he made a good point. Kendra has always expected us to drop everything for her. She wanted her siblings closer to her, John moved to the city next to her. She wanted to start a business, I'm expected to drop my small business to help her find events. But thinking this way has me wondering if I am being selfish.

So, AITA for choosing an event over my family.