From my point of view, starting from post one of this thread, it's the best thing that could possibly happen. She dumped you. She kissed someone else. She found out that you are the guy she really wants. Happy End. Make sure you get Hugh Grant for your role in the movie version.
I guess it depends on what you feel and what you want to do. Please take what I say with a grain of salt, as I never was in your situation and, in addition, have dropped my own relationship best practices and morals as soon as I could have used them.
Method 1: Unconditional Surrender
Take her back. Live happily ever after.
Method 2: Pout
Reject her. Regret it.
Method 3: Make sure she wants you
Give her a certain timespan ( a month maybe ? ) to decide what she wants. Tell her that you won't date anyone in this timespan and you will wait for her answer. Don't take any answer before the timespan is up. Don't ask or even mind what she is doing in this timespan. If she wants you, proceed to step 1. If not... well, it would not have lasted for long anyway.
Please note that Method 3 is the theory. I'm a weak willed coward myself and would immediatly try method 1.
