My boyfriend's ex.... what would you do?

So, my boyfriend and I have 2 years together , and since we are in this relationship I've noticed that one way or another, his ex keep in contact with him. At the beginning I just ignored this because u understand that she was broken (he broke up with her) and she felt needy, but 2 years and still in the map? I don't know what to think.... I confronted my partner many times, and he always says that she is the one who talks to him and say hi, as he doesn't want to be rude because he respects her.. But I believe that he is disrespecting me when he talks to her! Maybe I'm too paranoid because of my past relationships.. He says that if he wanted to return with her, he just clap his hands and she will be here. But that he loves me and she is in the past.. But whyy the hell he keeps in contact then???. Don't get it...