The affair wasn't revealed until Cecilia Brooks, pregnant with her sixth child, was told she had blood poisoning.
Her husband Bert Brooks, a building contractor, had arrived at their Te Ore Ore home near Masterton to find her weeping.
She told him that if she died he would find a letter behind the washstand.
How long Bert waited before reading the letter isn't clear in the Herald report of his successful action in the Supreme Court to divorce her on grounds of adultery.
What is clear is that the letter contained a confession of her affair with wealthy Wairarapa sheep