Catholic Church Teaching No. 1: those proclaimed in the Bible to be in Heaven, and those canonized as Saints, are the ONLY people we know for certain where they went after death.
Catholic Church Teaching No. 2: “Objectively”, it is proper to state that those who die NOT in a state of grace are consigned to Hell. To die in a state of grace is to die without sin on one’s soul, whether (1) through living a life without ever having committed a sin (the only two people Catholics have been taught did this were Jesus and Mary) or (2) by expressing sincere sorrow for one’s sins before death at confession or who was prevented from confessing due to circumstances, such as trapped in in rubble by an earthquake, yet still sincerely confessed one’s sins before dying.
Catholic Church Teaching No. 3: “Subjectively”, we must NEVER pronounce judgment of damnation on anyone in particular, as none of us but God has a window into another man’s soul at the time of his death, and it is a sin to do so.
In sum, it is safe to “conclude for argument’s sake” that Judas went to Hell for the sin of killing himself. One cannot be truly sorry before one commits a sin. It is impossible to be sorry for having killed yourself because you have a chance to repent until the moment of death, but it is the death itself for which you must be sorry and, unfortunately, YOU are the one who is dying . . .
The sin of betraying Jesus is a bit more “cloudy” as far as whether he was truly sorry. One need only look at the following passage:
Matthew 27:3 “Then Judas, who betrayed him, seeing that he was condemned, repenting himself, brought back the thirty pieces of silver to the chief priests and ancients . . .”
It is not very clear if the word “repenting himself” means “repent” in the modern-day sense of “having asked God for forgiveness for sinning” vs. “having merely acknowledged to the Chief Priest, Sanhedrin, and Pharisees that he made a mistake”.