The obvious solution is to cancel the party, and tell Jim that it was canceled. Then, if you want, create a new party, invite the people you wanted to come to begin with, don't tell Jim, and *have a spine* if he tries to find out information about it. And, honestly, nobody ever seems to just tell the perpetrator, "No, you aren't invited, because you keep inviting other people to a party that is not your own." If they'd told him that and he still did it, *then* these more elaborate ideas could come into play. But first, they need to open their mouths and tell him no.