If you are this dramatic over something as trivial as this, I hate to see what your reaction would be if something bigger happened, like a pony was not as described or damaged/lost in the mail.
Uh, sorry sweetheart, but no I would not feel the same way as you do right now.
I don't stress over trivial things like this. It's so not worth what you are putting yourself through at the moment, over a pony. I've been in the pony community for several years now (over 5 I think), and this has happened to me more times than I can remember, and my reaction is pretty much always the same.
I shrug my shoulders and say oh well, maybe next time instead of getting all up in arms about a pony that was sold before I could get to it.
I don't get upset or over dramatic because someone didn't update their list. And I can't say that I have really have anyone crab at me becasue I sold something they wanted and didn't have it marked as sold. I guess the people I normally deal with are a lot more laid back.
It happens all the time, and its something you will most likely have to get used to, not just within the pony community but in life outside of the internet. Maybe with a little more time in the community (I am assuming that you are newer in the community, seeing you joined here in Oct '08 you will find a way to not get so stressed over such trivial things.