Did I Trap Myself? (3-3 PL at the Vic)

[JFB37]

90% of the time I would raise the pot here on the flop but I was definately trying to trap. Risky, perhaps, but I thought the board justified it. There was no flush draw, only a straight draw, and no overs. I'm not positive he would have called a flop raise but think it is more likely than not that he would have.

On the turn, the one hand I could rule out for sure was a set of Kings, based on his pf play. Certainly there was a good chance that he had the nuts when he put me all in. However, I think he would have done this with 99 and my hand was reasonably well disguised. He could have been putting me on AA and trying to get me to lay it down.

The reason I posted the hand is because it raises the following general problem: when someone makes a big bet like this there is X% chance that he has the nuts but just how big does X have to be before you lay down the second nuts? [I considered my hand the second nuts because, as stated I was virtually certain he didn't have KK.]