It seems to me that you are suffering from a particularly modern twist on self-absorbtion.
It seems that you simply can't grasp that your actions have negatively impacted someone else or, if you can, you don't really care. After all, the situation suits you fine - you found your umbrella - so what's the problem, really?
The "other people do worse" defence is particularly ridiculous - that one will let you excuse yourself for just about anything short of murder!
Reneging on your bargain is one (very annoying) thing, but to do it and then profess to not be bothered about the inconvenience (and possibly worry) you've caused someone and hold them up for ridicule and censure - as you've done on this thread - is another.
We all do things to inconvenience other people at times, but a decent person genuinely apologises for it, which involves understanding that you are in the wrong, saying so and accepting the other person's right to be annoyed with us. It doesn't involve a cursory "sorry" followed by outrage that the other person still thinks poorly of you and appealing to the masses to tell you you're not in the wrong.
By itself, this is a minor incident in the scheme of things, yes, but your "I'm the main character" attitude (of which I expect you're completely unaware given how common it is) has annoyed me, I'm afraid! And if everyone behaves like you (which, more and more, they are) it makes the world just that little bit of a worse, more mannerless, more difficult, place to be.
So yes, YABU!