1-2 nlhe, optional $5 straddle. I have $750, villain is effective with $600. I’m utg+1 with two red kings. There’s a $5 button straddle by villain. I open for $15. Villain calls. Heads up. Flop is Qc9c7h. I bet $25 into $33 pot. Villain calls. Turn is 8s. I bet $65 into $83 pot. Villain calls. River is Kc. I hit my set but fd flush also comes in. Pot is $213. I don’t like my spot at all. Bet or check? I finally decide to bet $150. Villain raises to $400. I know I should never bet that river without being able to fold but really hate to fold a set of Kings. Plus his river bet sizing seems weird. Why not shove instead of leaving around $I00 behind. I tank a bit and finally fold. Villain shows Ah 10s for a busted straight draw. So, bad fold? Bad bet sizing post-flop? Thanks.