Can a realtor back out of an agreement for exclusive right to sell after she has signed the agreement and agreed to price?

I signed the agreement for exclusive right to sell on March 23, 2009 where listing price was agreed on. Yesterday, 5 days before the house went on the market the realtor said if we did not lower the price she would not work with us. Is she violating the agreement we signed by walking away if we don't do what she wants.