50 NL- Flop set...river brings every draw

[BJLTNYK]

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

BB ($55)
UTG ($58.65)
MP ($58.80)
Hero ($52.25)
Button ($49.25)
SB ($76.80)

Preflop: Hero is CO with 3[img]/images/graemlins/spade.gif[/img], 3[img]/images/graemlins/heart.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">MP raises to $1.5</font>, Hero calls $1.50, Button calls $1.50, <font color="#666666">2 folds</font>.

Flop: ($5.25) 8[img]/images/graemlins/heart.gif[/img], 6[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">MP bets $3</font>, Hero calls $3, Button folds.

Turn: ($11.25) 9[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">MP bets $8</font>, <font color="#CC3333">Hero raises to $21</font>, MP calls $13.

River: ($53.25) 7[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">MP bets $33.3 (All-In)</font>, Hero ???

My friend thinks this is an easy fold. I really wanted to not even look at the river after my turn raise. I'm probably spewing here alot but how often?