Regret?

So my ex and I still talk. It's odd that we ended our relationship on good terms. Is there regret in us ending? Yes and no. You see on the night we broke up I kept something to myself. When she asked if I was thinking the same thing she was, I should have told her the truth. What I did do was agree with her. Was it wrong to do it. She's happy now and married to a great guy. Who knows we may have gone downhill and not ended up speaking to each other. It will always be that I wonder the what ifs and sit on the fense thinking. To regret or not to regret. That is the question.