Surviving the attack on a centered king

This game was played during a live chess session in which my opponent played the ruy lopez but brought his bishop to c4 instead.  After a knight sac, my king was put into immediate danger, and I had to think carefully to pull off the win.  I would like the chess.com community to analyze this game and tell me if you see moves that me or my opponent missed that could have led to a different outcome.  Thank you for your analyses.

the fried liver? thats not good to play with black. you have to sacrifice a pawn with 5...na5 because 6.nxf7 is too dangerous

Could you give me a line that's a "for sure" success with the liver attack?  I guessing that my opponent made errors if so.

Personally, I don't like 5... Na5 much, I prefer the Fritz Variation, 5... Nd5.

Check out this topic: http://www.chess.com/forum/view/chess-openings/two-knights-fritz-variation

That's an interesting game!