This past weekend my (26f) friend (also 26f) threw herself an early birthday party. “Sarah’s” party was a planned hour long activity from 10:30a-11:30a but I told her originally I had no other plans that day so I could hangout with her for the rest of the day too. The day before her party, I found out my 35f friend, “Amy” wanted to last minute throw herself a birthday party as well that same day since it was her actual birthday that day. Day of, I went to Sarah’s party at 10:30am. Afterwards, most of us went with her to get lunch. At lunch I told her that Amy was also having a birthday party that night but that I wasn’t sure yet if I was going to go or not because I’m not too close with Amy. Sarah didn’t reply to this statement. After lunch, everyone left but 4 of us. We went to the mall, then back to her house and hung out. Come 6:30pm I told her I was gonna head out so I could stop by Amy’s party as well to celebrate her birthday, and she was noticeably instantly upset. Now Sarah’s been texting me that she’s mad I left her birthday for someone else’s birthday who I’m less close to when I originally said I could be with her the whole day and how she doesn’t know why it even mattered that it was Amy’s actual day of birth. She also was watching my location and is mad that I spent the night at Amy’s house (because I was too drunk to drive home) because I was with Amy for more total hours than I was with her. She got so mad to the point that she told me the next day coming up that’s important to me, she’s going to make sure to make other plans on it since I left her birthday early. None of our other friends have agreed with her side but also none of them have agreed with me either, but she’s so so angry. AITA?