Why did Hinton end his relationship with Perhacs?

After Hinton's appeals were denied, Perhacs wrote Hinton and told him that they could petition to the U.S. Supreme Court for a review of Hinton's case. However, Perhacs needed $15,000 to file the appeal. Hinton did not have that amount of money and he would not allow his mother to mortgage her house, so he ended his relationship with Perhacs.