Check or bet, that is the question

[Saborion]

UTG is 37/6/1.1 and 39/48 over 140h.
MP is 26/18/2.5 and 44/51 over 2900h.
CO is 19/15/3.1 and 38/53 over 800h.
Button is 49/23/1.3 and 48/46 over 100h.

I put the CO top pair + straight draw, KJ or a flush draw. With that high AF + high WSD he's likely to have put in another raise on the flop or turn with 2 pair or better. Or?
Buttons cold-call on the flop can be a lot of hands.

So, what is the best course of action on the river?

Party Poker 5.00/10.00 Hold'em <font color="#0000FF">(6 handed)</font> link

Preflop: Hero is SB with K[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/club.gif[/img].
UTG calls, MP calls, CO calls, Button calls, <font color="#CC3333">Hero raises</font>, BB calls, UTG calls, MP calls, CO calls, Button calls.

Flop: (12.00 SB) Q[img]/images/graemlins/diamond.gif[/img], T[img]/images/graemlins/club.gif[/img], 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(6 players)</font>
<font color="#CC3333">Hero bets</font>, BB calls, UTG calls, MP calls, <font color="#CC3333">CO raises</font>, Button calls, <font color="#CC3333">Hero 3-bets</font>, BB folds, UTG folds, MP folds, CO calls, Button calls.

Turn: (12.00 BB) 5[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets</font>, CO calls, Button calls.

River: (15.00 BB) 2[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)