What do I need to do in this situation?

My wife and I have been married for coming up on 2 years. I myself have always been a very negative person and have always looked at the bad or wrong in something. I have been working hard to change my outlooks and it has been making a very positive change to my life. One of the biggest problems my wife and I have been having over the years before marriage and after is her and guy friends. I guess with my negative thinking I was always looking at these guys as wanting to take her from me. So over the years she has gotten so that she keeps a lot of stuff from me so that I do not fuss or get mad. The most recent is that a guy that is a regular at the bar at which she works on weekends have become friends to where they talk on the phone a few times a week. Now my wife is 23 and this guy is 40. I try to look at the age as a sign that there is nothing there but lets face it age means nothing in this day and time. He is also very good looking and sucessful. Now my wife told me they have been talking openly which I really respected and it made me feel good but in my opinion she is a married woman and does not need that type of relationship with a man who is nearly twice her age. How should I talk to her about this without hurting her willingness to be open to me?