Does divorce occur if I utter the phrase: "Divorce upon me if Real Madrid plays better than Barcelona," intending to emphasize the truthfulness of my words during a discussion, knowing that I was indeed truthful? And is expiation incumbent upon me?

As long as you swore truthfully according to your belief, your oath does not result in divorce, nor does it require expiation, even if the matter was, in reality, contrary to what you swore about. For whoever swears about something believing it to be true, and it turns out to be otherwise, there is no divorce upon him. Know that swearing by divorce is forbidden in Islamic law; it is among the oaths of the dissolute. Some scholars have deemed it forbidden, while others have deemed it reprehensible. Even worse is when swearing by divorce is done for trivial matters that a sensible person should not occupy his time with.