Note that in [Luke 10 : 20], when Christ asked the disciples to rejoice that their names were written in heaven, Judas was in their midst. He played an active role in the apostolic ministry alongside the other eleven. [Act 1: 17]. Devil hadn't entered him then [Luke 22: 3]


Jesus regarded Judas as unclean [ John 13: 10, 11, 27].
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Also, from [John 15: 1- 6], Judas was abscent from amidst the disciples when Christ regarded them as clean; though cleansed, Christ warned them of being cut off from the vine if they refuse to abide in him. [John 15: 6].
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The core of Christianity is not just professing to accept Christ but also abiding in him. Hence, Jesus' words to Peter emphasizing repentance w.r.t. abiding in him [Luke 22: 31,32].
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John tried to explain this in [1 John 2: 1 - 6, 3: 9 - 10].
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There's no record of Judas' repentance but there is of Peter's. Repentance is not just a feeling of remorse, even Judas felt remorseful, unbelievers feel remorseful too. Remorse naturally comes with wrong doings except your heart has hardened over time. Repentance is returning from error with faith in the finished work of Christ [ Luke 15: 17, 20, 24; 1john 1: 9]
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With respect to abiding, read through the words of:
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JESUS CHRIST [ John 15: 6 - 8]
PAUL [Titus 2: 11 - 12; Rom 6: 1 - 4]
HEBREWS WRITER [Heb 12: 14 -16]
JAMES [James 5: 19, 20]
PETER [2 Peter 3: 13 - 17]
JOHN [1 John 1: 5 - 9; 2: 19; 3: 9 - 10]
JUDE [ Jude 1: 3 - 6, 20 - 23]
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JOHN OF PATMOS (Revelation of Jesus Christ Himself)
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To the Church of:
1. Ephesus [Rev 2: 5, 7]
2. Smyrna [ Rev 2: 10, 11]
3. Pergamum [Rev 2: 16, 17]
4. Thyatira [ Rev 2: 21- 29]
5. Sardis [Rev 3: 2 - 6]
6. Philadelphia [Rev 3: 8, 10 - 13]
7. Laodicea [Rev 3: 15, 16, 19 - 22]
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In conclusion, don't forget Jesus is coming
[Rev 22: 7 - 21]