Does a divorce take effect if a man says to his wife: "If you return to this action, then my wife is divorced," and his intention was to deter himself, not to effect a divorce? And how can he expiate for weighty oaths that he broke, the number of which he does not know?

Watching pornography is a heinous sin, and you must repent and seek forgiveness. If you do not return to watching those sites, then there is nothing upon you. If you return to them a second time, then a divorce has occurred according to the majority of scholars. However, Sheikh Al-Islam Ibn Taymiyyah holds that an expiation for an oath is required if you did not intend divorce.

Should a divorce occur upon watching again, you may reconcile with your wife before her iddah (waiting period) is complete, provided this divorce does not complete the three divorces. The iddah ends with her purification from the third menstrual cycle after the divorce, or after three months for one who does not menstruate, or upon delivering the child for a pregnant woman. If this divorce completes the three, then she is unlawful for you until she marries another husband.

Regarding the oaths you broke: If they were oaths by Allah Almighty and you do not know their number, then offer a number of expiations that you believe will clear your conscience. Fasting is not sufficient for an expiation of an oath unless one is unable to feed ten needy people, or clothe them, or free a slave. If the aforementioned oaths were divorce oaths, then you must consult a scholar to clarify what you uttered.