PokerStars 1/2 Hold'em (9 handed)

Preflop: Hero is SB with , .
UTG calls, 2 folds, MP2 calls, 2 folds, Button calls, Hero raises, BB calls, UTG calls, MP2 calls, Button 3-bets, Hero caps, BB calls, UTG calls, MP2 calls, Button calls.

Flop: (20 SB) , , (5 players)
Hero checks, BB checks, UTG checks, MP2 bets, Button raises, Hero 3-bets, BB folds, UTG folds, MP2 calls, Button caps, Hero calls, MP2 calls.

Turn: (15 BB) (3 players)
Hero bets, MP2 calls, Button raises, Hero 3-bets, MP2 calls, Button calls.

River: (24 BB) (3 players)
Hero bets, MP2 raises, Button calls, Hero 3-bets, Button calls.

Final Pot: 29.87 BB

Results in white below:
Hero has Ks Kd (four of a kind, kings).
MP2 has 9s 9d (full house, nines full of kings).
Button has As Ah (two pair, aces and kings).
Outcome: Hero wins 29.87 BB.

I guess I made my hand on the turn, but I felt weird about the hand on the flop since I find out later that I was beat 2 ways at the time, and it felt like it. So lets say the turn bricks out, are you prepared to check/fold this? If MP2 checks again continuing the slow play, it's gonna suck for me to call the buttons bets and be stuck in between when MP2 then has a chance to raise, if it were HU, I think I'd like a check/call to get to showdown at that point with that kind of money in the pot.