How do I go about this?

So I bought a Subaru legacy 07 for $3500, the seller told me the radiator needed to be switched so I did, then went to drive the car home and it overheated, the car says the head gasket was done and the seller told me he had no clue. Later on (because the seller is a business partner of my father in law) I met the seller in his office and his girlfriend in whoms car this actually was before I bought it and upon hearing our conversation cuts her partner (the seller) off and starts talking about how the car has had the same head gasket problem since they got it back from the shop. The seller sold me this for top dollar while knowing the head gasket problem made the car worth less than $1000 while he had me pay $3500 under false pretenses, is there anything I can do?