Did you read the sales contract? They usually say that if the buyer doesn't go through with the purchase for any other reason but not getting a mortgage, the buyer will lose the deposit. Also, the seller can force/sue the buyer for - I think it's called "specific performance". The court can make a buyer buy if he has the finances in order.
The selling and buying a home is one of the hugest things in an ordinary person's life. There are stringent laws that doesn't let the buyer walk for no reason other than spite at the last minute.
So, try not to worry too much.
"Worry is like a rocking chair. It keeps you going, but doesn't get you anywhere". I have no clue who said that, but I agree with it...
In the meantime, I'm going to have all my crossables crossed for you. Do let us know what happens.
Dolly