Seems to me it would take a lot more time and effort to tell people in person rather than just writing a quick note for everyone to

You know what, don't bother.

I'm not in the mood right now.

And I'm sure that next time, you'll be less careless. Or you'll actually do us the courtesy of telling us if we're really invited or not. If you want an invite-only, send out invites. That's all.