No where in the bible does it say you have to marry the person you sleep with. (Chill out people. No where does it LITERALLY say that. It's an interpretation.) Marriage also, didn't used to be legally documented, but a promise to one another! It's a stupid religious implication. I think God would be fine if you marry him, yes, but if you loved him at the time it's fine. If you're still worried go to confession at a Catholic church. But the lines of right and wrong or too vague. You're much better behaved than 70% of the world.
I think you'll be fine. :o) In no way is having sex with the love of your life immoral!
(And I think that you should also pay attention to the fact that the religious people on here were freaking rude and judgmental. They didn't offer advice or preach God, but judged. That is only God's place and they should be ashamed. If every sin is the same, than they are being just as naughty on here judging you! If you're really sorry and choose Jesus, you'll be forgiven! He forgave the prostitute in the bible!)