If you have honestly committed your life to Jesus Christ and are trusting Him alone for your salvation, then the Bible says that God has forgiven you -- fully and freely. You have been adopted into His family, and nothing can ever change that. The Bible says, "Therefore, there is now no condemnation for those who are in Christ Jesus" (Romans 8:1).
Don't trust your feelings; they aren't dependable and will only lead you astray. Instead, trust Christ and what He has done for you by His death on the cross and His resurrection from the dead. Trust, too, in God's promises to you -- because God cannot lie, and He has promised to forgive and save all who come to Christ by faith.
In addition, ask God to help you forgive yourself. The memory of what you did in the past condemns you -- but it condemns you falsely, because Jesus Christ gave His life for all those sins. The Bible says, "We set our hearts at rest in his presence whenever our hearts condemn us. For God is greater than our hearts" (1 John 3:19-20). If God has forgiven you, shouldn't you also forgive yourself?
Thank God for His forgiveness -- and then ask Him to free you from the past. In addition, if possible go back to those you hurt, and let them know you regret what you did and you hope they'll forgive you -- even as Christ has forgiven you.