seller breach of contract -- please help!

[Mon Kaaaaaa]

We recently went into contract with hopes to move in 3 weeks, but the seller is backing out. We received a call from his realtor saying that there he has a pre-payment penalty on his loan and that he has nowhere to live (his house has been on the market for 7 months and he didn't consider all this?...yeah right). The following day the realtor calls back saying that he first thought he couldn't get a loan but now he might be able to get one so then he was still going to sell it. Then today we received a ""cancellation of contract"". Can the seller do this? What are my rights and options?

Please help."