Seller signed purchase agreement in LA and now wants to back out

[Jonathan Norris]

I entered into an agreement with a neighbor to purchase a property in Reseda for $600,000. The seller informed me that she did not want to get an agent involved that she wanted to sell it privately. She told me another investor was interested but she will get back to me the next day with an answer. The next day she called and wanted me to rush so she can sign the purchase agreement. It was signed. Today, she wanted to back out of the deal. I believe the other investor may have offered her more money. Can she back out the deal? Can the other investor but my contract? What are my options still still receive some sort of money if I have a signed contract?