Horrible behavior to play with your mind this way. You do not see it for what it is?

It is possible that seeing you married has evoked a feeling of being threatened in him - threatened that you might leave him altogether, and, feeling threatened and apprehensive of the possibility of losing you has, in turn, made him realize how deeply he feels for you, but he should have kept it to himself - he should not have burdened you with this twisted "love confession". Horrible behavior!!!

More likely, he is not even acting on the fear of losing you - he is just playing mind games with you. What is surprising is that you do not see it for yourself. You wrote that you are not naive, but you are being very naive. Look - if he truly did not want to come between your and your new husband, he would not have uttered his "love confession". Walking the walk and not just talking the talk, anybody? I think he is either being cruel, or, being extremely immature. In neither case does he love you - a cruel man cannot love you, and an extremely immature man has not developed the capacity for loving in the first place.

I think you did the right thing declining to see him.