Is a wife Haram for her husband if he told her that a divorce had occurred, and he had sworn an oath of divorce with the intention of delaying it, then he asked a شيخ (sheikh) who gave him a fatwa that the divorce had not occurred, and then he divorced her another time?

An oath is based on the intention of the one swearing it. So, if the husband intended his wife to get up at any time, he does not break his oath by her delay in getting up. As for what he told his wife, that the Shaykh issued a fatwa that a divorce occurred, when in fact he did not issue such a fatwa, no divorce takes place by that statement, and he may take her back before her iddah is complete.