[lastchance]

Hero is 33% dog at worst. Even if he turns over the nut flush, you have 1/3 chance of hitting the full. (well, they could have top or middle set, but you just pay em off)

So, go out, bet or check-raise. I'd bet here, hoping to be called by two pair or a King of Diamonds. When raised by those hands or the flush, I either three bet all-in, or fold, depending on the odds.

If two people get their chips all in, you call, without a second doubt. You hit that full, and you have the best hand, almost no doubt.