What can be done if seller breaches real estate contract and committing fraud?

The seller in this contract has been less than forthcoming on the details of the onsite septic system. I didn't receive form 22ww until 3 days before close. Needless to say, the septic had not been pumped, inspected, or RSS conducted by the local Health Department. The septic fail inspection last year in March 2015. In May 2015, there is another report for an emergency service call because of backup. In form17 disclosure, the seller answered N/A for all questions concerning the septic. There is a septic report from 2002 when the seller bought the property that there were septic issues that needed to be addressed that never were. The seller just applied the Health Department for a current RSS and clearly answered that there were no malfunctions or repairs during his ownership of the home. In form 22ww section 5, it states I should receive maintenance records, but seller want produce. He offered pre closing occupancy until 8-5-16 only for an extension for closing on 7-29-16, that's not wise for my family. I countered with $2500 purchase price reduction with an extension until 8-9-16 to give him ample time to close. He want budge and I am due some type of compensation I feel. Now my agent wants to know if I want to terminate. I have no clue what to do. I'm a first timer and this is very frustrating.