I think it is more than that
peter never denied god in his heart. He sinned out of fear. And he had sorrow that he could not trust God enough.. Even more. God did not condemn him for it. In fact. peter never even confessed it. Jesus healed him by asking him three times, peter do you love me (actually in the greek, it says more than that the english is a poor defenition)
Judas was never saved, and never believed in God. Was sorry, because he knew Jesus was a righteous man all the less. And the people lied to him.. he di not have godly sorrow. He had human sorrow..