If you can show that the seller lied about or misrepresented critical facts (like lied about known problems or issues), then you can show he committed fraud: fraud is both grounds to void, or get out of the agreement and to sue the seller for compensation (such as to get back some or all of the money you paid).Also, landlords--and if you are on a rent to own, until you own it, he is your landlord--have an obligation to provide habitable space. Issues that make a place unsafe or unhealthy to live in (like no heat; certain bad or dangerous plumbing or electrical problems; mold) violate that obligation (called the "implied warranty of habitability") and can provide grounds to terminate the contract and again to sue for compensation--such as part of your rent back, for having lived with such conditions.You therefore seem to have good defenses to being liable under the contract and may have grounds to sue him as well. If you leave the home and stop paying and he sues you, you are strongly advised to retain an attorney to not only help defend you but to counterclaim against the seller, to recover compensation for you.