kinda pissed at my ex

So I have a co-parenting agreement with my ex.

In it there is a clause to the other parent meeting a new partner before the new partner meets our kid, I feel that is important in terms of respect and to ensure a good relationship between the parents and the new partners..

I know my ex told me a lot of negative stuff about what his ex said about me and I really don't want that to be an occurrence, I want to have a decent relationship with his new partner, which will only benefit the kids imo.

So today my ex is bringing his new partner over to meet his kids and I'm kinda pissed because obviously I haven't met her and that isn't what we agreed upon.

He then proceeds to tell me he never actually really agreed with that (he did sign it) and that I met his kids without meeting his ex and he doesn't think it's that important.

I was a literal child when I met his kids (I was 21, he was 36) and that is part of the reason why I want to meet her first.

I don't mind that he's moving on, I wish him the best, I wish her the best and I want her to feel welcome in the family. (if they're going to be a part of my kid's life, they're family) I want her to know I'm not jealous, I'm open to her being there and I'm grateful for her to make my ex a happy person. He knows this. He tells me she's insecure about me being present (I see my ex quite regularly because of his schedule/our kid) so I think this might be important for her as well, to know that I want to welcome her into the family.

What do you guys think?