The Last Supper

The Last Supper, Simon Ushakov, 1685

When evening came, Jesus was reclining at the table with the Twelve. And while they were eating, he said, 'I tell you the truth, one of you will betray me.'
They were very sad and began to say to him one after the other, 'Surely not I, Lord?'
Jesus replied, 'The one who has dipped his hand into the bowl with me will betray me. The Son of Man will go just as it is written about him. But woe to that man who betrays the Son of Man! It would be better for him if he had not been born.'
Then Judas, the one who would betray him, said, 'Surely not I, Rabbi?'
Jesus answered, 'Yes, it is you.'
(Matthew 26:20-25)

I think if I was Judas I would have been pretty scared. I wonder why the other disciples didn't try and stop him?