Have I uttered a divorce in my mentioned situation, and does it take effect if the utterance was "Nabila, I have divorced," knowing that Nabila is not my wife's name?

What happened to you are illusions and whispers, which have no consequence, and the divorce of one who suffers from obsessive whispers does not occur. Certainty in the continuation of the marital bond is not removed by doubt regarding divorce. The best way to overcome obsessive whispers is to completely ignore them, thereby vexing Satan, in addition to seeking refuge in Allah from his evil and resorting to ruqyah (Islamic exorcism).