What is the ruling regarding a man saying to his wife: "I divorce my wife if I do not fondle and kiss a woman other than you, then I am an illegitimate child," and what are the implications of this oath, and how can one be absolved from it?

Firstly, swearing by divorce is forbidden, and it is not permissible to accuse a Muslim of sins. The aforementioned utterance constitutes a conditional divorce, which, according to the majority of scholars, takes effect if the condition it is contingent upon is not met. However, Sheikh al-Islam Ibn Taymiyyah holds the view that one can be absolved from it by offering an expiation for an oath (kaffarat yamin (definition)) if the intent was to threaten and not to divorce. The questioner can marry a second wife to lawfully engage in what the divorce was made contingent upon.