rent to own agreement in arkansas

my husband and I are in a rent to own agreement in Arkansas. We exercised the option to buy after 11 months of paying rent. We made our first $2000 down payment on March 1, 2010. We paid it again in March 2011. We cannot afford to make that yearly payment anymore. I pay house payments weekly. I am always on time. We want to get out of this situation, but the Lessor says that we have to fulfill the contract until 2015. If we move, we are responsible for rent on another home plus this one until we/ she finds another tenant to fulfill this current contract. If we stay here and dont pay the $2000 payment by April 1st, all of the weekly payments I make will go straight to the $2000 payment until it is paid off, then the weekly payments will resume plus all of the late fees. Either way, I think she will evict us because we cannot afford the late fees ($2/day) and she will pile them up on us. We will be so far behind, we will never catch up.