My ear cartilage was fractured/split internally. No outer laceration. How long does the swelling subsides?

You know your anatomical terms but how do you know its fractured?  If so, you likely had a hematoma and if that happened, you have a chance of developing a cauliflower ear as you continue to heal.  At this point, if your swelling is resolved, all you can do is wait and see.  If you're still swollen, you can consider seeing a surgeon to see if there is still blood present that can be removed.  Bottom line, you should see an ENT or plastic surgeon for an evaluation.