I don't understand why going public is to important to you. She may just be a private person and she feels that you breaking up is none of their business. She may just feel embarrassed or uncomfortable and she chooses to keep it to herself. I would let her deal with this in her own way. You have not told either. The same way you have your feelings about the situation she has hers. Work is not the best place to be giving out personal information. Some people just want their business to be more private. Tell serves no purpose but to get people talking. She may not want her relationship to be the talk of the office. If you want to reunite then you should just let her do this in her own time. The better you handle this breakup the better you will look in her eyes. If you start the conversation at the office she may see that as a violation to her trust. Let her handle it.
Please press accept; this is the only way I am compensated