How about offering your services and then taking that offer back?
Sorry, blue, but acting butthurt about the band changing their mind whilst openly admitting that you were about to do exactly the same to them is not only illogical, it's also hypocritical. And openly stating that you're not surprised by what you misinterpret as an unprofessional outlook by most of us here is pretty insulting to the general TB membership, as is your "I'm right and almost everyone else is wrong" schtick that most folks outgrow before they hit their twenties. In fact, I know plenty of musicians in their twenties with way more maturity than that. I think some of your issues aren't anything to do with being too old and more to do with never having really grown up. Nothing too wrong with that in some ways - I'm dreading the day when I have to act like a grown up.
You got away without having to honour a commitment you'd made, but wished you hadn't made. The band got their bassist slot filled. It sounds like nobody's burned any bridges. So, there's absolutely no sensible reason for anyone to keep whining about this situation. Please, quit doing that before you lose what remains of your credibility on this forum. Sorry to be so blunt, but it's pathetic to hear someone your age complaining like this. Folks our age are supposed to set an example for all those high-schoolers you keep taking a dig at.
It would be great for you to stop making yourself miserable about your music and enjoy the fact that you're still doing it after all this time. I'm grateful every day that I'm lucky enough to do that and get a lot of pleasure out of it. If music's making you this unhappy, why carry on at all?