do i have to bye my short sale property if i bank give to me only verbal approwal and i still didnt have a contract for this?

I put the offer for short sale property in October 2012. June 13 i called my lawyer and ask him if i can walk away without any consequences. My contract expired February. His secretary said she will call me back. Never happened. June 14 my real estate agent txt me and told me i have verbal approval and now i have to wait for written one. Do i still can walk away or in that situation i have to go with this. I don't want the seller keep my down payment. Thank you