My first comment may surprise you, but I’m thankful you feel this way about your past. If you just laughed about it, or dismissed it as unimportant, or didn’t feel any guilt over what you’ve done and the people you’ve hurt, then you’d be in great spiritual danger, because you wouldn’t feel any need for God. But you do feel guilty, and because you do, you’ve taken your first step toward seeking God’s forgiveness.
But you’re wrong when you say God can’t forgive you because you can’t forgive yourself! Is God less powerful than you? Is God less loving than you? To put it another way, are God’s hands tied until you get your own life in order? No, of course not. Jesus Christ didn’t wait until we were perfect to give His life for us. The Bible says, “God demonstrates his own love for us in this: While we were still sinners, Christ died for us” (Romans 5:8).
God’s forgiveness is a gift—a gift He freely offers us when we repent of our sins and turn in faith to Christ. Why refuse His gift any longer? The Bible says, “For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord” (Romans 6:23).
Then, ask God to help you put your past behind you. He may want you to apologize to those you’ve hurt and ask for their forgiveness. But don’t be bound by the past; God has already forgiven it.