The best revenge of all is Happiness. Nothing drives people crazier than seeing someone have an incredibly good Life.
If you go around being sad all day and feeling sorry for yourself people won’t want to be around you. That certain someone who left you will also believe that they made the right decision.
If you really want to drive that certain someone crazy find your happiness without them. Show them that you are the one who is better off. When you find your happiness you will find the person who loves you the most… Yourself.