You've been free of his lies and treachery for months. Your divorce is about to be processed. Unfortunately, much like that filthy STD that his "secretary" gave him and he shared with you, something about him remains as a semi-permanent reminder of the pain: his last name.
You've considered keeping it. After all, it's been your last name for some time now. All of your vital records, your professional license, and even your birth certificate are now under your married name. Nonetheless, every time you sign that seven- (or however many) lettered abomination, you become nauseated.
It's time to move on.