Should I trust him of let go if he doesn't stop calling his ex?

My husband and I met and began dating in 2007, he was 42 and I 26. I knew from the beginning he was in touch with his ex of ump-teen years. They met in high school. However, he did cheat on me with her yet continues to say they are only friends and will never be more. Before we got married he promised me to stop calling her. Almost one year later I found out he's been calling her literally every morning while at work. He says they talk about us. He gets womanly advice from her about our marriage. But in the start of our relationship she hated the fact that he was falling in love with me. She told me herself he would marry me way before it was discussed between me and him. She did also say he would more than likely not stop calling her though, and he hasn't. I've been holding off on getting my name changed because I just don't like it and don't know if I should trust him. Sometimes I think of divorce. I've been told by a few older women not to worry about it. He's always home and takes good care of our family. Should I trust him or demand if he doesn't stop calling her by our anniversary (Feb. 27) I want out?