Soo first post and on mobile but I really have to get some objective opinions on this.

So yesterday my best friend and I had planned to meet up. I have been going trough some personal shit and really needed support and was looking forward to seeing her. We planned this a week or so in advance. So about half an hour before we decide to meet up she canceled on me because she just discovered that she had to go to her boyfriends brothers birthday, which was moved to today. She offered to hang out for half an hour before she had to go but I declined and got slightly mad about the fact that she found this more important. Would have been understanding if it was her boyfriends birthday, but it was his brothers birthday who she has only met once or twice I believe.

So am I justified to be slightly mad and annoyed about this or am I acting like an asshole.