KK in RR pot - AAx flop

[xwowsersx]

The PF overcaller/flop donkouter is running @ 86/0/0.4 - clearly an ultra loose and passive fish. The 3-bettor in this hand is running @ 28/27/13. I decided to call here and check raise most flops b/c the RRer is 3 betting pretty liberally and will definitely Cbet most any flop.

Poker Stars, $2/$4 NL Hold'em Cash Game, 5 Players

SB: $1,300.70
BB: $400
UTG: $1,000.40
Hero (CO): $571.50
BTN: $400

Pre-Flop: K[img]/images/graemlins/heart.gif[/img] K[img]/images/graemlins/club.gif[/img] dealt to Hero (CO)
UTG folds, <font color="red">Hero raises to $16</font>, <font color="red">BTN raises to $52</font>, SB calls $50, BB folds, Hero calls $36

Flop: ($160) A[img]/images/graemlins/heart.gif[/img] 2[img]/images/graemlins/diamond.gif[/img] A[img]/images/graemlins/club.gif[/img] (3 Players)
<font color="red">SB bets $64</font> Hero ... ?

Thoughts on how to proceed in the hand?