River Decision Against Aggressive Freak

[Subby]

For better or worse these super-aggressive players are bringing out the uber-aggression in me pre-flop and then my utter disdain for their holdings the rest of the hand. Is my river decision here a clear fold?

UTG is 53/29/4.12 after about 30 hands.

Party Poker 5/10 Hold'em (6 max, 6 handed) converter

Preflop: Hero is CO with 9[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/heart.gif[/img].
<font color="#CC3333">UTG raises</font>, <font color="#666666">1 fold</font>, <font color="#CC3333">Hero 3-bets</font>, Button calls, <font color="#666666">2 folds</font>, UTG calls.

Flop: (10.40 SB) 2[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/club.gif[/img], 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, Hero checks, Button checks.

Turn: (5.20 BB) 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">UTG bets</font>, <font color="#CC3333">Hero raises</font>, Button folds, <font color="#CC3333">UTG 3-bets</font>, Hero calls.

River: (11.20 BB) K[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">UTG bets</font>, Hero ... ?

Final Pot: 13.20 BB