Was what happened a khul' or a divorce, and what is the 'iddah required of the woman in this case?

What transpired between you is a khul', which is considered an annulment (faskh) and not a divorce (talaq), because every word indicating separation in exchange for compensation is a khul'. The compensation here is your relinquishment of the deferred mahr and the movables. The woman who undergoes khul' observes an 'iddah of one menstrual cycle, according to the more preponderant opinion. Since khul' is an annulment, it is not counted as part of the number of divorces. If you both agree to a new marriage contract after the 'iddah expires, the husband will have three pronouncements of divorce at his disposal.