How many people are there that you cannot stand? People that you avoid? What did they do to make you feel this way?

Fortunately, there is only one person that I cannot stand. It is my fiancé's ex-girlfriend. One year after we began dating, she started coming around all of the time. It was weird. All of a sudden, one year after breaking up with him, out of the blue, she started calling and showing up at his door and his parent's door. My fiancé (boyfriend at the time) finally told her she needs to go away. That was seven years ago and it still irks me. Who does she think she is? If I see her car somewhere, I won't go there.