To not want to pay for a party for DS cos ex is inviting their partner and family?

[c3pu]

My ex and I spoke about organising a party for DS at a local soft play, and going halves on the cost. Sounded fine, so I agreed in principle, but nothing more was mentioned about it for months.

Fast forward to this morning, and my ex gets in touch about booking it up. Only now it transpires that not only is it a kids party, but my ex is inviting lots of family and partner.

I said that's not the sort of event I want to pay into, as my family won't want to attend as my ex has been rude to them in the past, and my ex doesn't want my partner there either (which isn't so unreasonable as we've not been together long).

Am I being unreasonable to not want to shell out for a party where I'm going to be marginalised?

The whole thing is ridiculous. Why do any adults need to be there besides you and your ex? How many kids are invited?

How long have you been with your girlfriend OP?

It read to me like he was told, at very least made to feel uncomfortable about inviting them - if I'm incorrect the OP can correct me.

And I also have no idea why anybody would want to go to a soft play centre!

Don't hold a separate party but don't contribute anything financially to this event which is a thinly disguised get-together for her family. The dc won't give a hoot which adults are there while they play, and you can do a "birthday treat" outing on another day that isn't a competing party.