One of life's hardest lessons is that we can't go back and change the past. Once something is done it can't be undone; all we can do is face the consequences. Tragically, we often don't realize this truth until it's too late—but perhaps your letter will be a warning to someone who needs it.
No, we can't change the past–but with God's help we can change the future! And the most important truth I can tell you is that God loves you, and He wants to give you hope for the future. He wants to forgive your sins–not only whatever you did that may have shortened your life, but every other sin you ever committed. Most of all, He wants to take you to heaven someday, so that you can be with Him throughout all eternity.
You see, God loves you so much that He sent His only Son into the world to die for you. You and I deserve to die for our sins–but all our sins were placed on Christ, and He died in our place. Now He offers us the gift of eternal life–no matter who we are or what we have done.
Don't let your guilt or anything else keep you from Christ. God's promise is for you: "To all who received him, to those who believed in his name, he gave the right to become children of God" (John 1:12). By a simple prayer of faith ask Jesus Christ to forgive you and come into your life today–and He will.