Wrong to back of with KK here?

[luckydonut]

PokerStars 2/4 Hold'em (9 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Preflop: Hero is UTG+1 with K[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/club.gif[/img].
UTG calls, <font color="#CC3333">Hero raises</font>, MP1 calls, MP2 calls, <font color="#666666">1 fold</font>, <font color="#CC3333">CO 3-bets</font>, <font color="#666666">3 folds</font>, UTG folds, <font color="#CC3333">Hero caps</font>, MP1 calls, MP2 calls, CO calls.

Flop: (18.50 SB) J[img]/images/graemlins/club.gif[/img], 8[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets</font>, MP1 calls, MP2 calls, <font color="#CC3333">CO raises</font>, <font color="#CC3333">Hero 3-bets</font>, MP1 folds, MP2 calls, CO calls.

Turn: (14.25 BB) 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, MP2 checks, <font color="#CC3333">CO bets</font>, Hero calls, MP2 calls.

River: (17.25 BB) 2[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, MP2 checks, <font color="#CC3333">CO bets</font>, Hero calls, MP2 calls.

Final Pot: 20.25 BB
<font color="#009B00">Main Pot: 20.25 BB, between Hero, MP2 and CO.</font> &gt; <font color="#FFFFFF">Split: Hero (10.12 BB), CO (10.12 BB).</font>

Results in white below: <font color="#FFFFFF">
Hero has Ks Kc (two pair, kings and eights).
MP2 has Jh Qh (two pair, jacks and eights).
CO has Kd Kh (two pair, kings and eights).
Outcome: Hero wins 10.12 BB. CO wins 10.12 BB. </font>


I figure that with CO making it 3-bets pre-flop and still showing aggression on this flop that I am probably against a large pocket pair. Given that we beat QQ but are crushed by AA or JJ, should I still be leading the betting on the turn. I'm don't think I'm ahead of CO here more than 50% of the time.

However with MP2 still in the pot and looking like he is way behind, is the chance to get his extra money in the pot reason enough to keep betting for the times that we are ahead? Or do we want to try to force him out of the hand to increase our chances of taking this pot?

I'd already had KK vs AA and QQ vs KK earlier in the session so I'm sure that affected my decision here. Should I still be throwing more money at this hand until more strength is shown by either opponent?