When to give up with the nut flush draw

[jakbse]

Party Poker 1/2 Hold'em (10 handed) converter

Preflop: Hero is MP2 with K[img]/images/graemlins/diamond.gif[/img], T[img]/images/graemlins/diamond.gif[/img].
UTG calls, UTG+1 calls, <font color="#666666">1 fold</font>, MP1 calls, Hero calls, <font color="#666666">1 fold</font>, <font color="#CC3333">CO raises</font>, <font color="#666666">2 folds</font>, BB calls, UTG calls, UTG+1 calls, MP1 calls, Hero calls.

Flop: (12.50 SB) A[img]/images/graemlins/diamond.gif[/img], 8[img]/images/graemlins/diamond.gif[/img], 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(6 players)</font>
BB checks, UTG checks, UTG+1 checks, <font color="#CC3333">MP1 bets</font>, Hero calls, CO folds, BB calls, UTG folds, UTG+1 folds.

Turn: (7.75 BB) 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">MP1 bets</font>, Hero calls, <font color="#CC3333">BB raises</font>, <font color="#CC3333">MP1 3-bets</font>, Hero calls, <font color="#CC3333">BB caps</font>, MP1 calls, Hero calls.

On theturn I have nine outs to the nut flush and the pot is 9,75 BB when the action comes to me the first time. I should call, no problem. When BB starts raising I put him on something between a big two pair and a house. But I can´t possibly find a fold except on the river where I´m sure an overcall is a misstake.

River: (19.75 BB) Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">BB bets</font>, MP1 calls, Hero folds.

Final Pot: 21.75 BB