What to do the builder did not gave flat a built on my land

My father & his brothers made a contract with a developer to build and erect a building on our land. They gave him their power of attorney. He agreed to deliver certain flats first to them and then he could sell other flats. But still now he could not complete the project but already took money from people for seeling the flats without informing us and also without giving us any flat . Now flatowners filed suits against him as well as us as respondents claiming money with interst. My father died a year ago so they made me a party. I am contesting. But my humble question is what have i done wrong? Can I have the chance to be relieved? What should I do ?