Folding straight when river pairs the board

[ImNotSoLucky]

Advice on turn welcome as well, but mostly curious what your typical river line is. Villain has total aggression of 1.3 over just a few hundred hands. No other info

Full Tilt No-Limit Hold'em, $2 BB (6 handed) Full Tilt Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

SB ($211.35)
Hero ($205)
UTG ($260.55)
MP ($200.10)
CO ($211.10)
Button ($436.85)

Preflop: Hero is BB with 5[img]/images/graemlins/spade.gif[/img], 7[img]/images/graemlins/club.gif[/img].
UTG calls $2, <font color="#666666">3 folds</font>, SB completes, Hero checks.

Flop: ($6) 8[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/club.gif[/img], 4[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, Hero checks, UTG checks.

Turn: ($6) 6[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets $4</font>, <font color="#CC3333">UTG raises to $12</font>, SB folds, <font color="#CC3333">Hero raises to $34</font>, UTG calls $18.

River: ($70) 6[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $32</font>, <font color="#CC3333">UTG raises to $111</font>, Hero folds.

Final Pot: $134