We see an interesting comparison between the lives of Judas and Peter. They both followed Jesus and knew Him personally. They both betrayed Him. Yet the stories end very differently. Judas realized he sinned and kind of tried to make it right by returning the silver but still took matters into his own hands instead of forgiving himself and moving on. Peter, on the other hand, wept after he realized his sin but continued serving God; and the resurrected Jesus restored him!
Do not let your mistakes define you! You can always, always repent and turn back to God and be used by Him again! That is the beauty of grace and forgiveness!