Consider for a moment the similarity between Peter and Judas. Peter denied Christ, Judas betrayed him, but both of them were guilty of basically the same offense. Peter did it to avoid embarrassment and possible persecution, and Judas did it for money. Both men did despicable wrong against their Savior.
Now consider what makes them so different from each other. When Judas saw that he had made a horrible mistake, he committed suicide. The End. Peter, on the other hand, had a talk with Jesus about it and received forgiveness, restored fellowship with the Lord, and the chance to preach at Pentecost.
There comes a time in every young person's life when you feel like you've really blown it. At some point after you mess up, you ask yourself, "What was I thinking?!" No doubt both Peter and Judas thought the same thing. Now you have two options. You can go out and ruin the rest of your life (Judas) or you can hang on long enough to get it straightened out with the Lord (Peter).
If you've had a "Peter moment," hang on a second! Jesus is there for you, ready to help you out of that sin. Just be humble enough to repent, submit and move on with life. Even though Peter's denial must have hurt Jesus deeply, He looked past Peter's faults and saw Pentecost. When we screw up, He doesn't say, "Look what you did!" He says, "Serve Me!"
Judas didn't have to hang himself. He could have talked it out with the Lord like Peter did in John 21. Just think, we could have a book of Judas! He could have lived the dream that Peter did! But no...
When the time comes that you feel like you've made the biggest mistake of your life, do what Peter did. Repent, submit, obey, press on, and move on. You don't have to live a defeated Christian life just because of one mess up. God has a future planned out for you. Get back up, get it straight and keep on serving the Lord!