Graciela del Castillo, 61, and kids Pablo and Maria Laura were devastated when Guillermo, 63, lost his battle to cancer.
The Argentinian family paid to place a death notice in the local paper, but were shocked to spot a second notice printed beneath their own, which was dedicated to a man with the same name in the same town.
Guillermo's unusual name meant they were suspicious, particularly as the message read: "My dear little fatty. Thanks for these five years of happiness. Your love for ever, Susana."
It soon became clear that the family man had actually been sharing a second home with mistress Susanna Cegada, 45.
Son Pablo was quoted in the Daily Mirror admitting: "My mother is devastated. None of us had the faintest idea. He was often away on business but we never suspected."
And family friend Fusiano Godinez confirmed the affair: "He spent part of the week with one family and the rest with the other. You would never have guessed it to look at him."
Susanna also took to Facebook to dedicate a tribute to her deceased love, saying: "I will miss your calls, your scent, your touch, your voice saying sweet words to me, telling me 'My little dumpling, you are beautiful'."
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