Your friend is right: You can be forgiven, and you can know beyond doubt that someday you will go to be with God in heaven forever. And my prayer is that you will take the one step that is necessary for this to become a reality. What is that step? It is the step of faith - trusting Jesus Christ as your Lord and Savior and committing your life to Him.
Let me explain what this means. Only one thing will ever keep us out of heaven, and that is our sin. God is holy and pure, and unless we are cleansed of our sins we can never enter heaven. The Bible says of God, "Your eyes are too pure to look on evil; you cannot tolerate wrong" (Habakkuk 1:13). We not only need to be forgiven; we need to be cleansed.
But how is this possible? We can't cleanse ourselves; only God can do it. And this is what He did by sending His Son, Jesus, into the world. He was without sin - but on the cross all our sins were placed on Him, and He took the judgment we deserved. All this was in accordance with God's plan, for God loves us and wanted to provide a way for us to be cleansed and saved.
What must we do? We must turn to Christ, repenting of our sins and trusting Him alone for our salvation. Why not ask Christ to come into your life right now and save you? The Bible says, "Believe in the Lord Jesus, and you will be saved" (Acts 16:31).