The Big Blind just wouldn't fold

This is a hand from about a week ago. It's 4-8 Hold'em ($1 and $2 blinds) at the Monte Carlo on the Vegas Strip (best small poker room on the Strip!) and the game is typical with a few loosies and a couple decent players.


The hand:


A couple early position players limp and a respectable middle postion player raises. I expect this means he has either a big pair or possibly AK. I don't think he's raised with anything else so far. No callers to me in the cutoff. I've got AcTc. I can expect the early limpers to call the raise so I call as well. The big blind and early limpers call. 5 players see the flop.


The flop is: Kd,Qd,Jd


That flop looks a bit coordinated. I've got a straight and it seems very likely that the pre-flop raiser has a set. If the board doesn't pair, he's in for a surprise. If it does pair, I'm folding. Of course, I've got to be leary of a made-flush which I'm drawing dead against.


All four players check to me and I bet. I can't let a stiff diamond get a free card and my bet may scare out the Td, 9d or 8d who may think their drawing dead against me. The big blind calls. Both early positon players fold and then the MP (pre-flop raiser) check-raises me. No surprise there. He's either got a set or he's got AA or AK with the Ad. Maybe he has TT with the Td but I seriously doubt it. Either way, I'm ahead of him. I decide to just call so that I can raise on the turn to drive out the big blind who I put on a single stiff diamond.


The turn is: Kd,Qd,Jd,4c


Good turn card and everything goes according to plan. The big blind checks. The MP bets and I raise to get the hand heads-up. But then... the big blind 3-bets! I get an empty feeling inside. The MP calls and I reach for my chips to stubbornly call the hand down since I've got the "nut" straight. As I'm about to put my chips in front of me, I stop and finally think about it. "What could he possibly be three-betting with this board?" I ask myself. After a moment, the answer comes--"Duh!".


I fold.


Did I put too much money into this pot with a three-flush on the flop?


Results in a moment.