How small a one card flush can I draw to?

[Stealthy]

Reads not important. Just the normal mix of LAGs and calling stations.

Party Poker 3/6 Hold'em (6 max, 6 handed) converter

Preflop: Hero is Button with A[img]/images/graemlins/club.gif[/img], J[img]/images/graemlins/spade.gif[/img].
UTG calls, MP calls, CO calls, <font color="#CC3333">Hero raises</font>, <font color="#CC3333">SB 3-bets</font>, <font color="#666666">1 fold</font>, UTG calls, MP calls, CO folds, <font color="#CC3333">Hero caps</font>, SB calls, UTG calls, MP calls.

I thought the CAP was easy given the amount of bad hands already in and my good position over the 3 bettor.

Flop: (18 SB) Q[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/spade.gif[/img], 3[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">SB bets</font>, UTG calls, MP calls, Hero?

Well the pot is big but I could be drawing dead, is this an easy fold or an easy continue? How far can I take this hand if I carry on? How much does the decision change if the Queen [img]/images/graemlins/spade.gif[/img] is replaced by a different [img]/images/graemlins/spade.gif[/img]. I am not keen on spiking an Ace given the action so far but I may be committed to a showdown if an Ace or my flush comes in.

This was my first foray into $3 $6 6 Max and my first time playing these stakes.

Thoughts?