Feeling for you, I was in a somewhat similar situation, me and my wife both fell in love with her best friend, jealously wound up coming into the picture with my wife and she sought another male relationship... i could not have anything to do with that as I am straight and jealous of other men. When she had her dealing with the other man I was no where to be found, but I also found it just made my feelings for her best friend intensify. Made me question my marriage and wonder if I had married the right woman. I never remember being loved the way her best friend loved me, may have been the mixture of NRE and finding security after being wounded...
Sorry this post was just more of a relation rather than any advice as I have been struggling with finding my truth for the last six years. Good luck my friend.