Song from Soldier to wife from war....?

This is a song about a Soldier who writes a letter to his wife. But
one other wife "gets" it. She thinks its for her but it is really for
her neighbor. She believes her husband has died but it is her
neighbor's husband. The two husbands both know each other and the
lyrics have something to do about "carrying on" or "moving on" or
"keep living". Thanks so much.