AIBU for not inviting my partner’s dad to my daughter’s party?

[JohnnyP3n]

So, I'm organising a birthday party for my daughter's birthday with my ex. My new girlfriend has just been introduced to my ex and that circle of friends, which is great, but she wants to invite her dad to the party as well. My ex hasn't met him yet although my children all have and like him.

I personally think it might not be quite the right occasion to be introducing him, as it might blindside my ex, and I've upset my partner by not inviting him.

AIBU?

@girlmom21 “Double figures is a milestone for lots of people”

Are you really saying that a girl’s mum who would be fine with it at 9 or 11, would not like it happening at a 10th birthday? In the context, it is really not a milestone birthday party, just a run around the park.