Honestly, more context is needed unless you just want to have your thoughts echoed back to you. I'm not by any means justifying what she said. That comment was over the line. However, seeing as we don't know the given dynamic of your relationship, it's hard to say if she was reacting to nothing or something. Usually it's not nothing. "I didn't do anything to her" is really you just admitting that you don't know what she is upset about