Answer:
Simple...don't tell her:). The best thing to do would be to avoid her but I'm guessing you've already tried that. Take her aside, tell her that you are getting hurt by her behaviour and tell her where she is going wrong and immediately afterwards, ask her if there is anyway you can improve in order to enhance the friendship.
There is nothing wrong in being critical of others but be humble enough to offer yourself to a little criticism as well :)