What is the ruling on breaking an oath sworn to a woman not to marry her, knowing that the oath was made after an argument and before consummation?

If by your oath you intended to threaten your wife with divorce, then divorce does not occur by the mere oath, nor are you obligated to carry out the threat. However, you are obligated to offer expiation for an oath (kaffarat yamin) if you do not divorce her at the time you intended, or at the last possible time for divorce (the death of either of you) if you did not specify a time. Some scholars hold that expiation becomes obligatory merely by your intention not to divorce her.