Seller backing out of retail building

[Ash Patel]

I have a $400k retail building under contract in Ohio and the seller informed my realtor that he wants to back out because of family politics. This was a standard residential contract, all cash and as is.  I read through the forums and couldn't find examples of litigation in this type of case.  I am willing to spend the money to pursue litigation.  The closing is scheduled in 7 days.  Any advice or experience?