I agree with OP i've been in spots like this a lot lately, and bet the flop hard, get called, and then see a scare card (another spade) and feel stuck. Even if checking the turn, the river usually sees a bet by him. painful to let go, but too often any call sees 2s5s or some such.

So, from tigerite's note, if he rr over the pot+ bet, call. if he flat calls and turn brings a low spade... then what?
If villian checks?
If villian bets (there's 685 in pot by now if flop bet was 200, and villian's got 370 left to Hero's 535 or so)

From my memory I always end up allin and lose and hate slick. Of course, I probably don't remmeber the times he folds or I get him drawing and nothing comes.