If God can forgive you--and it sounds like he has--then your significant other should forgive you as well, just as God has forgiven him. Believe it or not, sin is sin. There are no "worse" sins. Yes, you've come into the relationship unpure, but he is not pure either, in the sense that he has lied before, or cheated, or done anything else sinful. Instead of tallying it all up, he should forgive you and show you God's love. If he can't, I'd question his faith, since forgiveness is such an essential part of a relationship with God. It may take time for him to forgive you, but he should forgive you. If he can't, and he still tells you he feels cheated, it sounds like you need to find someone else, someone who understands what forgiveness truly is.