I'll be using some generalizations for obvious reason.

So today I've had a fun happening. Something new was opening today, and few days ago me and friends decided to go there. Opening day isn't a big deal, it'd be the same the next day, but hey, we were hyped to be first to check it out.

The reason why I'm writing this is because my sister (really close to the wall, I'm in early 20s) called me today around noon asking if I could go do some things for her, because it was her name day and her current beta has invited her for a dinner. I usually do that because I do have my own benefit in it, and if she called few days before I'd definitely accept. But under these circumstances I refused. The opening was to be at 7pm, and if I were to do her a favor I'd end it around 9pm.

Cue the usual bitching, her saying that her appointment is more important than mine, hanging up, insulting me via SMS, calling our mother to bitch to her so she would try to convince me, etc. You get the gist.

Few calls from her, few calls from our mother, about half-way she started crying which I didn't really phase me. In the end I've decided to maybe drop it after all, and right before calling I felt my gut clenching, I'd like some insight on that. So the call was short, I told her that I could drop it, she said she doesn't need my mercy and then I simply hang up to get ready.

Now, I feel like apologizing, for a simple reason. The opening was postponed by a day. We arrived there, saw the note on the door, and yeah, I felt pretty bad after it sank in. We hanged out and had fun, but it's not something we couldn't do on another day.

So yeah, that's the story, more or less. Should I man up, explain the situation, and apologize, or is that not manning up but just pussying up, and just be convinced that I did the right thing for standing up?