Can I fold TPGK in a HU pot?

[waffle]

BB defense hand. Button is a TAG that has a decent sized stealing range on the button and I'm in the BB.

We've been at this table a while and we have a little history. I've defended and c/f'ed the flop a few times. I've c/r'ed the flop a few times. He folded to my subsequent turn bet twice.

The third time, he called my flop c/r with A6 high, turned a 6, and called turn and river bets with a couple of overcards in the playing zone on board. His hand was not good.

PokerStars 2/4 Hold'em (5 handed) FTR converter on zerodivide.cx

Preflop: Hero is BB with Q[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/club.gif[/img].
<font color="#666666">2 folds</font>, <font color="#CC3333">Button raises</font>, <font color="#666666">1 fold</font>, Hero calls.

Flop: (4.50 SB) 7[img]/images/graemlins/club.gif[/img], Q[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">Button bets</font>, <font color="#CC3333">Hero raises</font>, Button calls.

Turn: (4.25 BB) T[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">Button raises</font>,

I never, ever, ever fold this. Should I think about it? (Obviously I'm calling the turn with my 4 flush. But what if I didn't have the four flush? And, with it, should I fold on river if I don't it?)

I think a few people will say 3bet PF. I'm open to discussing the merits of this but I don't want to make this the main thrust of the thread. I currently mix it up.