NL 50 - KK - did I eff this hand up?

[I'mVeryBusy]

PokerStars No-Limit Hold'em, $0.50 BB (7 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

MP2 ($61.85)
CO =#A500AF(villian)/ ($48.75)
Button ($149.25)
SB ($46.95)
Hero ($48.75)
UTG ($51.65)
MP1 ($48)

Preflop: Hero is BB with K, K.
[color=#666666]3 folds</font>, [color=#CC3333]CO =#A500AF(villian)/ raises to $2</font>, [color=#666666]2 folds</font>, [color=#CC3333]Hero raises to $6</font>, CO =#A500AF(villian)/ calls $4.

Flop: ($12.25) 4, 7, 3 [color=#0000FF](2 players)</font>
[color=#CC3333]Hero bets $9.5</font>, villian calls $9.50.

Turn: ($31.25) 6 [color=#0000FF](2 players)</font>
Hero checks, [color=#CC3333]villian bets $22.25</font>, [color=#CC3333]Hero raises to $33.25</font>, villian calls $11 (All-In).

River: ($0) 8 [color=#0000FF](2 players, 1 all-in)</font>

Final Pot: $97.75

Results in white below: [color=#FFFFFF]
Hero has Ks Kh (one pair, kings).
villian has 8s 7s (two pair, eights and sevens).
Outcome: villian wins $97.75. </font>

Villian stats are 36/9/1.5

I really didnt think he had the str8 with that bet. Did I botch this? I checked because I wasn't sure about the straight and then his bet gave me my answer. I can't help but think I could have played this better. Thoughts?