[3/6] I suck at Rivers -- AA OOP vs. Possible Flush

[Xhad]

Lately I've noticed I seize up and turn loose/passive on the river too often. Sorry if this seems obvious but as I said, I suck at these situations right now.

Villain is 18/11.8/2.4 after 161 hands but this is my very first hand at this particular table.

Party Poker 3/6 Hold'em (10 handed) internettexasholdem.com

Preflop: Hero is BB with A[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/spade.gif[/img].
<font color="#666666">5 folds</font>, <font color="#CC3333">Villain raises</font>, <font color="#666666">3 folds</font>, <font color="#CC3333">Hero 3-bets</font>, Villain calls.

Flop: (6.33 SB) 5[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/diamond.gif[/img], 7[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">Villain raises</font>, <font color="#CC3333">Hero 3-bets</font>, Villain calls.

Turn: (6.16 BB) K[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, Villain calls.

River: (8.16 BB) 5[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>

Hero???