Halloween w/His Kids & Ex-wife

Understandably due to Covid, we weren't sure if we'd be doing anything tonight.

He called me around 430 and said he'd like for us (he & I) to take our children to a few houses to keep the spirit of Halloween. I said okay as we weren't doing anything. 630 rolls around no show. So I called no answer. It's getting dark so I go ahead and leave and take my 2. Afterwards, I called again and it's going straight to VM. He sends a text to say he and his ex ended up taking their children together.

I understand but I am kinda pissed that #1 We're together and you won't take my call in front of her? She already knows about me. #2 Why wasn't I told this initially rather than making plans with my children and me?

I guess I want to know if I have a right to be upset?

**just realized I had a few typos. Sorry about that**