There are two factors which you do not see to be considering:
- Judas knew exactly what he was doing. Matthew 27:3,4 Then Judas, which had betrayed him, when he saw that he was condemned, repented himself, and brought again the thirty pieces of silver to the chief priests and elders, saying, I have sinned in that I have betrayed the innocent blood. And they said, What is that to us? see thou to that.
- Even though, having admitted his sin, Judas could have been forgiven, he committed suicide before that forgiveness could be extended to him.
I hope you have found this helpful.