I dunno. I've stayed out of this one, but I'll chime in. You probably could have still saved face, and maybe still can.
But overcharging on shipping is just a form of price gouging. I don't mind overpaying a bit on shipping as people have to procure supplies. We all recycle a lot, but at some point you're buying packaging tape or markers or printer paper or something. But otherwise, I'll refund someone even a small amount (except for the $.05 to my recent Canadian buyer...sorry, gotta stick it to the Canucks, keep them in their place!). I do that because I've been shanked on shipping, mostly on eBay, and it's a crappy thing to do.
Anyhow, I don't have much of a stake in this, but stepping back from the issue and not getting caught up in a frenzy of posting against a mass of like-minded boardies might serve you well.