Seeing an old friend

tonight I had dinner with what most will call a ex-boyfriend. We dated prior to me meeting Danny. It was casual and not so casual. When I met Danny we were out with friends and my so called ex told me that he saw a connection between Danny and I that he hadn't seen.  He was the one who told me not to let this pass. I have always appreciated him for that. He is now married and he met for dinner. We talked about danny and those early days when he knew danny and I were meant to be.  I was happy to be able to talk with an old friend but felt guilty at the same time. Nothing was between this old friend of mine but I came home feeling sad and bad as though I had done something wrong. I miss Danny so much that I feel empty.  I need stength