played it fine unless you have a reason to turn the K into a bluff on the flop vs the fishy player

I usually give credit until I see something out of line to call down in these spots. He could be valuebetting a worse flush if hes bad but thats rare

I think the SB is very likely to hold the m Ace of s in his hand.
Without knowledge of the players preflop range and postflop tendencies I opt to fold here. Also given you don't have any redraws I think going with it is gonna be substantial -EV.