K-Js hearts. That's the only hand i can see villian holding on this hand, un. I would lean towards K-Js playing weak on the flop, and reverse bluffing the river hoping to induce a call. Too hard to say for sure whether he was bluffing or not, but you're beat far too often in this spot to call. I think a fold was the smart and proper play to make. I would not have played the hand any differently.