5-handed late-night cbury must move. Villain is, as far as I can tell, a solid/thinking/winning reg. He normally plays the 30/40 games, but only the 20 is going this night. Clearly knows how to play well. I've been getting a bunch of hands and have been raising a ton PF but haven't shipped too many pots. Neither of us have gotten out of line. No real history between us either.
I open from the CO, villain 3! sb, weak/passive bb calls two cold, I call.
Flop: Kxxtt. No clubs. Villain bets, bb folds, I have a strong hand and I call intending to raise turn (would have raised flop had bb called).
Turn: KxxTtt. Villain bets, I raise, villain pauses for a moment and 3!. Board has two spades and two hearts.
Two questions:
First, villain has Q

J

. Is this really such a great turn for the 3! semibluff? I feel like he's ahead against anything I'm bluffing with and will never get me to fold anything I'm raising for value. It's been a while since I've played shorthanded poker with aggressive/thinking players, is this 3! standard?
Second, does anyone ever fold a king here? A ten? I have K

8

, which rivers do I fold?