How we will know that my husband is devoted to you and care for you.?

my husband is a divorce, he hav 3 kids 12 yrs old, 14 yrs old and 16 yrs old.. and his ex wife will call to our house bec of the kids, sometimes my husband answer the phone but i am very very angry to his ex and i hate her specially my husband talk to her in the phone, what should i do.and how we will know that my husband is care for me and she hav no feleings to her ex they been together for almost 10 yrs thats why i never believe to my self that she hav no love to his ex.. help me pls..