I don't agree, Lofty.
I would tell a pal, but I would never, ever, ever tell anyone else.
My rule is simple - one hundred percent loyalty to your friend, and NO ONE else.
By the same principle, if a friend told me she was having an affair, no one else would EVER hear it from me.
There are no grey areas. You tell your friend EVERYTHING, and you tell everyone else NOTHING.
No blurry edges.
No gossiping.
No nothing.
Just complete and unquestioning loyalty.
Having said which, your "don't tell" argument is just as valid.