The Son of man goeth as it is written of him: but woe unto that man by whom the Son of man is betrayed! it had been good for that man if he had not been born. (Matthew 26:24)
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. And he cast down the pieces of silver in the temple, and departed, and went and hanged himself. (Matthew 27:3-5)
For godly sorrow worketh repentance to salvation not to be repented of: but the sorrow of the world worketh death. (2 Corinthians 7:10)
The more accurate translations indicated he was remorseful and regretted what he had done. But that's different than repentence. True repentence does not result in suicide.
Perhaps Judas made a fatal mistake when, upon realizing he’d sinned, confessed to the “chief priests and elders”. As an Apostle, he should well have known to go to Christ Himself for forgiveness.