What document do I file to express my right to a deposit made on a business purchase that did not close?

My husband and I, as officers of our privately held corp, placed a deposit on a business we intended to purchase. The purchase went bad and the seller is suing us for the deposit (we believe we have solid grounds to pull out of the deal.) When my husband and the trustee put the money into escrow, my name was not on the deposit, so I am not named in the suit. My husband has since filed bankruptcy and lost rights to the money, but I still have a right to half. What document do I file to claim my right? Third party something? Thanks in advance.