I have more questions than answers I'm afraid. Was there a written contract? Was the deposit to "hold" the house - as in.... if you don't take it you loose your deposit or a "damage" deposit, - in case of damages to the property after you move out? My best advice is to seek help from an attorney.
Does the Idea of Integrity and Fair Play ever come into consideration any more?
Is everything about TAKING and never GIVING?
Is MONEY the only consideration?
And do we never think that the other person may have some troubles of their own?
It is so easy to justify; everyone else is out to get a piece of me!