Welcome to the Great Chain of Rejection that is publishing!
Think about it. The agonizing rejection we regularly enjoy as would-be scribblers is only the first link in a great chain of rejection:
- agents reject authors
- editors reject agents
- publishers (or internal surrogates like the publishing committee or the sales team) reject editors
- and readers reject publishers
Viewed in its entirety, it is a thing of beauty (cue Circle of Life from The Lion King). Your one small rejection is part of the great web of rejections that is publishing.
It's not fun, but it means you're living the writing life--where it is true that, "that which doesn't kill us makes us stronger."