50NL: KK River Decision

[Cougar]

Hello!! First post in SH section, was 50NL/100NL Full Ring, moved over to 6-Max recently, my background/history/approach is posted over in my Operations thread ("Progression").

Disclaimer: Not a MILF, Cougar was my mascot in high school

Apologies if this hand is straightforward, left a little unsettled about it...

Villain is pretty fishy but showed some limited aggression, 49/29/1.1, 60% fold to c-bet, 7% PF 3-Bet over 73 hands

PF: Put Villain on a pretty wide range PF

Flop: 3/4 PSB c-bet for value (2 clubs, 2 lower connectors near villain range)

Turn: Flush hits, chose to b/f 3/4 PSB (Value from Jx hands, value/protection from club draws, sets & lower made flushes will probably raise)

River: Decide to check, didn't really see much value in betting (what do I beat that will call?). Villain bets strong, representing Nut flush, made straight with a 7/2 or maybe some sort of 2 pair, although this villain might be fishy enough to have air. My initial thought was easy fold (need to be right ~30%) but then I started second guessing myself after and wanted to check with you guys

Better lines to take? Feel free to berate any street

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com
BB ($61.90)
Hero (UTG) ($57.75)
MP ($43.15)
CO ($50)
Button ($50)
SB ($74)
Preflop: Hero is UTG with K, K
Hero bets $2, MP calls $2, 4 folds
Flop: ($4.75) 5, 6, J (2 players)
Hero bets $3.50, MP calls $3.50
Turn: ($11.75) 3 (2 players)
Hero bets $8.50, MP calls $8.50
River: ($28.75) 4 (2 players)
Hero checks, MP bets $22, Hero ???