How could Jesus have a betraying disciple?

After saying these things, Jesus was troubled in his spirit, and testified, “Truly, truly, I say to you, one of you will betray me.” The disciples looked at one another, uncertain of whom he spoke. One of his disciples, whom Jesus loved, was reclining at table at Jesus’ side, so Simon Peter motioned to him to ask Jesus of whom he was speaking. So that disciple, leaning back against Jesus, said to him, “Lord, who is it?” Jesus answered, “It is he to whom I will give this morsel of bread when I have dipped it.” So when he had dipped the morsel, he gave it to Judas, the son of Simon Iscariot. Then after he had taken the morsel, Satan entered into him. Jesus said to him, “What you are going to do, do quickly.” Now no one at the table knew why he said this to him. Some thought that, because Judas had the moneybag, Jesus was telling him, “Buy what we need for the feast,” or that he should give something to the poor.

When morning came, all the chief priests and the elders of the people took counsel against Jesus to put him to death. And they bound him and led him away and delivered him over to Pilate the governor. Then when Judas, his betrayer, saw that Jesus was condemned, he changed his mind and brought back the thirty pieces of silver to the chief priests and the elders, saying, “I have sinned by betraying innocent blood.” They said, “What is that to us? See to it yourself.” And throwing down the pieces of silver into the temple, he departed, and he went and hanged himself. But the chief priests, taking the pieces of silver, said, “It is not lawful to put them into the treasury, since it is blood money.” So they took counsel and bought with them the potter’s field as a burial place for strangers. Therefore that field has been called the Field of Blood to this day. Then was fulfilled what had been spoken by the prophet Jeremiah, saying, “And they took the thirty pieces of silver, the price of him on whom a price had been set by some of the sons of Israel, and they gave them for the potter’s field, as the Lord directed me.”