When this man is conflicted about telling his step father in law about a family secret, he asks Reddit:
My wife’s side of the family & I have been keeping a secret from my SFIL for quite some time now. My therapist has suggested that I follow my wife’s wishes when decisions need to be made concerning her family.
This is something that I feel he should know. Her family & I all agree that no one should inform him of this secret because of the theoretical aftermath that would come.