God promises to forgive us our sin if we confess them.
1 John 1:9 If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
No need to *prove* how sorry for them you are.
That's just a show for men. God already knows.
And the best way to show that you've repented is to stop doing the sin, not pray a bunch of Hail Mary's and take a trip or two around the rosary.
16Therefore, confess your sins to one another and pray for one another, that you may be healed. The fervent prayer of a righteous person is very powerful. James 5
In the narrative that constitutes the first part of the fourth book of the gospel (Mt 13:54–17:27), Jesus is shown preparing for the establishment of his church with its teaching authority that will supplant the blind guidance of the Pharisees (Mt 15:13–14), whose teaching, curiously said to be that of the Sadducees also, is repudiated by Jesus as the norm for his disciples (Mt 16:6, 11–12). The church of Jesus will be built on Peter (Mt 16:18), who will be given authority to bind and loose on earth, an authority whose exercise will be confirmed in heaven (Mt 16:19). The metaphor of binding and loosing has a variety of meanings, among them that of giving authoritative teaching. This promise is made to Peter directly after he has confessed Jesus to be the Messiah, the Son of the living God (Mt 16:16), a confession that he has made as the result of revelation given to him by the heavenly Father (Mt 16:17); Matthew’s ecclesiology is based on his high christology.
Directly after that confession Jesus begins to instruct his disciples about how he must go the way of suffering and death (Mt 16:21). Peter, who has been praised for his confession, protests against this and receives from Jesus the sharpest of rebukes for attempting to deflect Jesus from his God-appointed destiny. The future rock upon whom the church will be built is still a man of “little faith” (see Mt 14:31). Both he and the other disciples must know not only that Jesus will have to suffer and die but that they too will have to follow him on the way of the cross if they are truly to be his disciples (Mt 16:24–25).