The Castaway by W. W. (William Wymark) Jacobs

On a cool night, an ill formed man darkens the doorway of Mrs. Boxer. Her trepidation turns to instant joy when she discovers it to be her long lost husband, who has been lost at sea for the past three years.
But the supposed Mr. Boxer has a suspicious mother in law. And when she secretly connives with an ancient fortune teller, new discoveries show that Mr. Boxer isn't the man he proclaims himself to be.