Final answer:
John's public confession of his affair was to discredit Abigail and save his wife; however, it leads to unintended consequences, showcasing situational irony.
Step-by-step explanation:
John's intention of publicly admitting his affair with Abigail was aimed at proving that he was not being controlled or influenced by her, and thus to discredit her and the other girls' accusations of witchcraft in the community.
This is ironic because his confession was intended to save his wife, Elizabeth, and his own integrity, yet it leads to further questioning of his character and damages his reputation even more. The type of irony here is situational irony, where the outcome is drastically different from what was expected.