Flop fold with TPTK in a 3 bet pot

[BDaws]

Reads: Villain is 49/21/2 over 60 hands. I don't really have many reads. I had 3 bet him an orbit or two earlier and he folded PF. That, plus the fact that he opened UTG led me to believe his range is a bit stronger than a typical loose bad player's would be for calling a 3 bet PF.

He lost a pretty big hand my first couple of hands at the table with TPTK against an overpair, but he was OOP was c/called down, so I don't put him on a TPTK that I beat. If he has TP, I suspect he has a decent draw to go with it, that or two pair.

PokerStars No-Limit Hold'em, $1.00 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Hero ($128.55)
BB ($71.90)
UTG ($267.30)
MP ($24.40)
CO ($176.60)
Button ($121.45)

Preflop: Hero is SB with A[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/spade.gif[/img].
<font color="#CC3333">UTG raises to $4</font>, <font color="#666666">3 folds</font>, <font color="#CC3333">Hero raises to $12</font>, <font color="#666666">1 fold</font>, UTG calls $8.

Flop: ($25) K[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/club.gif[/img], J[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $15</font>, <font color="#CC3333">UTG raises to $255.3</font>, Hero folds.

Final Pot: $295.30

I haven't played much since Partypoker shut down so I'm very rusty. Is this a bad fold? Looking back on it, I should've bet more on the flop. Probably around 18-20, right?