if i hurt someone, then i need to make things right with that person seeking forgiveness and making amends. and if that is not possible, then i turn to God saying listen, i cannot make things right with the person who i hurt but please forgive me for what i had done. God knows we are not perfect. we make mistakes - some major ones. i can't go back in time and erase the past. the past is the past. you live and you learn, growing as a person becoming a better human being. i can't live the rest of my life feeling awful and guilty for my past mistakes. it will hold me back from growing spiritually. you have to forgive yourself.
it is only in the life hereafter that we will all know if God has forgiven us. hopefully, we will have earned God's forgiveness. each and every day, you ask God for forgiveness and try to be good to yourself and others.