Should I be mad

I’m already insecure and depressed but last night my boyfriends ex phoned him ( his kids mom ) but she phoned on the daughters phone but I still got upset and hated the way he was speaking to her, he was being really nice like he still loves her, they have 2 kids together, their teenagers now so why can’t he go through his kids and not her? She phoned to tell him where his kids concert is but why couldn’t the kid do it