Thanks for the comments everyone. Greatly appreciated. I considered 3bet, but I was about to quit so I wanted to play a small fit and fold pot. Anyway, I snapped call with my AK on the river just to see that he has AA T_T. But as played, I guess it was correct to justify calling giving the 3:1 odds that many of you pointed out. Now it doesn't make me feel so bad anymore.
P/S: Hate it when I was up like nearly $500 for the night and then lost a big $200 pot as I was about to exit