Does what the husband did, uttering the words of divorce in various contexts—intending to joke, or to cite a reference, or to affirm that divorce had not occurred—necessitate divorce, knowing that the wife suffers from obsessive-compulsive disorder?

What was uttered by the husband was a narration of divorce, and divorce does not occur merely by narration. It is obligatory to disregard obsessive thoughts, not to pay attention to them, and to beware of persisting in them. Seek Allah's help and make abundant supplications to be rid of them.