Ugh. Gaslighting. Thppt.
Look, before you go further, take this to highlighter. Figure out if there's more wacko afoot, and what the fav playgrounds are.
This is just NOT going to work if you guys are not playing by the same ethical polybook game manual. There is mine and how I roll.
Conflict resolution framework? Something like that. http://www.mindtools.com/pages/article/newLDR_81.htm
Either put a lock on your door, or be the secondary in your house and he can go live with HER wherever she really lives be be the primaries over THERE during the experimental 30 days and coparent the children from the house home base.
The children most of all need to be stable.
The party stupid? It is stupid. You are the "downstairs neighbor." If there's a party in the upstairs apartment (even if you don't actually live in an apartment bldg) the polite thing is to give the neighbor the heads up there gonna be people around on (party date), parking all up and down the street, some noise and things. In a gesture of goodwill, invite the neighbor for a beer if they too want to come by for a bit, assure all the trash will disappear, and things won't get rowdy.
Nobody needs a pissed off neighbor and most of the time they don't even want
to come, but they feel more agreeable about putting up with the woowoo for the birthday or whatever if the gesture is at least made. Someday they want to have a party too and you will be nice about their birthday woowoo.
You didn't even get basic neighbor polite there. Sheesh.