24: The fact that Jesus would die on the coming day was already established. God had predetermined it, promised it, and prophesied it. The betrayer is still at fault, however. This shows the balance between Divine will and human will. God has determined the way of things in this evil world, but will offer mercy to each individual. Judas chose to betray Christ. It was an act of his own will.
Woe is pronounced only when great judgement is due. Indeed, Jesus, by his words, shows that Judas bears the greatest blame for his being brought to the point of crucifixion. The saying Jesus uses here concerning Judas was common among the Jews. It expressed a more complicated concept than might first be recognized. One who was never born would be a miscarriage. Such persons, never having the chance to enter this world in force, are presumably better off than those who, having been born, make a mess of their lives. The implication is that a miscarriage would have hope for the future, whereas Judas could look forward to nothing but eternal torment.
25: Judas seems to be trying to cover his bases before the other disciples. However, he may also have sincerely wondered if Jesus knew who would betray him. Either way, he did not expect the answer he received.
Judas called Jesus Rabbi rather than Lord, possibly trying to sound more respectful. Instead, he succeeded in being different from men who were obviously innocent. Jesus’ answer here is another common expression. Rather than saying yes, you say that the person has said it, but it means yes. Apparently, none but Judas heard his answer.