Some backstory. My mom has been dating this guy for about four years. Her and my dad have been divorced for over ten years so no issues with that. However, she told me she was engaged three days ago and was having her wedding today. I live three hours away with my fiancé and did not want to drive all the way there for a half an hour “ceremony” which was going to take place in her living room just to turn around and drive three hours back. The wedding is taking place at night and all my family was busy before hand so there was no one to even visit with before the wedding. 

She is upset at me but she needed to tell me more time in advance to possibly get off work on Monday. All my other siblings live within five minutes of her so she just never considered my distance and just assumed I’d make the trip. AITA?