What exactly is the condition upon which divorce was made contingent?

If you doubt the suspension of divorce upon two matters (your wife doing a specific thing, or your knowledge of it), then if your wife does the thing and you come to know of it, the divorce takes effect according to the majority of scholars. You can then take her back before her iddah (waiting period) expires. However, if your wife does the thing and you do not come to know of it, the divorce does not take effect, because the default is the continuation of the marital bond, and the certainty of marriage is not removed by doubt regarding divorce. Sheikh al-Islam Ibn Taymiyyah mentioned that an expiation for an oath (kaffarat yamin) is incumbent upon you if you did not intend divorce.