KK, flop comes with an Ace, never know what to do here?

[zach383z]

This hand is against a tough, yet exploitable TAG, 16/13 over 200 hands... Regardless of his tight image, I never know the correct move on this flop...

PokerStars No-Limit Hold'em, $0.25 BB (6 handed) Hand History converter Courtesy of PokerZion.com

UTG ($24.65)
MP ($25.55)
CO ($6.30)
Button ($5)
SB ($9.20)
Hero ($31.35)

Preflop: Hero is BB with K[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/spade.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">MP raises to $1</font>, <font color="#666666">3 folds</font>, <font color="#CC3333">Hero raises to $3.75</font>, MP calls $2.75.

Flop: ($7.60) 6[img]/images/graemlins/club.gif[/img], 6[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $3.75</font>, <font color="#CC3333">MP raises to $12</font>, Hero folds.

Final Pot: $23.35


Is my bet just way too weak or what do you guys do in this position...

Edited: realized I put the wrong stats for villian