Have you ever done something that you are not proud of? I know I have and the guilt you feel at times is overwhelming. God's word tell us that we are to go to the person we have wronged and ask for their forgiveness. Sometime we hang on to the guilt because we can't seem to forgive ourselves and we like to wallow in our own self pity. If the Almighty Creator can forgive us and forget our past transgressions why can't we? Life is too short to hang onto past sins/transgressions. Forgive yourself, get on with God's work, and you'll find that each day of your life will be better than the day before.
Once we, too, were foolish and disobedient. We were misled and became slaves to many lusts and pleasures. Our lives were full of evil and envy, and we hated each other. But "When God our Savior revealed his kindness and love, he saved us, not because of the righteous things we had done, but because of his mercy. He washed away our sins, giving us a new birth and a new life through the Holy Spirit." Titus 3:3-5