Is it a betrayal or not?

I am and have been involved in a serious relationship for the last year. My ex bf, who lives is another state, recently contacted me and said he'd like to meet me for lunch when he is in town. I love my bf, but would like to see the ex for lunch. We helped each other through a difficult time in our lives and have remained friends. Should I go or not? Would going be a betrayal to my bf?