Was Judas's greatest sin his betrayal of Christ or his despair of forgiveness?

His greatest sin, as the Bible keeps pointing out several times in the New Testament, was his betrayal of Christ, not his remorse. We do not even know that he thought he was beyond forgiveness; he may simply not have wanted to be forgiven, which is a possibility too. But the Bible keeps stressing that the betrayal was the great sin, so we do not need to compare anything else to it to know that is true.