easy fold. i would have checked the flop and folded to a bet unless he gives me a good price to see the turn. since there are 2 over cards on the board, and he called your preflop raise, you have to put him on one of those two overcards, probably the Q, he could possibly be holding AK. either way, i feel you are way behind, and he's not giving you very good odds
, 2:1, to chase your straight.
i'm still learning cash games, but this is how i would have played post flop.