Wife's ex

Hi All,

Wife and I have been married almost 8 years now and she keeps in close contact with her ex from high school. (texting & calls at least once a week) He is married as well and both couples have kids. He has not let go of the past and would leave his life for my wife in a heart beat. He sends inappropriate texts and if they ever meet out in public he always brings up what life could be. My wife deletes texts from her phone because they either would drive me nuts or are over the line. My wife assures me that he is nothing and I get worked up for no reason but she will not stop taking to him even though it bothers me so. She has told me she deletes text from him because she doesn't want to read & think about the past. I am a very loving husband and bend over backwards for her. I provide for my family and feel I take care of any of her needs above and beyond. I just can't get past this issue. He will not back down after all these years and I can't understand why he won't just let it go. I just want to stop thinking about this and move past because it puts me in a horrible mood and can't help but fear to lose my wife. How can I get over this? And before you say "dude, just stop thinking about it?" I've tried he always creeps back in lol. Help!