100+9: TPWK, and middle card on board paired on turn. Next move?

[AA suited]

Party Poker No-Limit Hold'em Tourney, Big Blind is t100 (6 handed) converter

HERO (t1955)
UTG (t3983)
MP (t1462)
CO (t815)
Button (t650)
SB (t1135)

Preflop: HERO is BB with K[img]/images/graemlins/diamond.gif[/img], 5[img]/images/graemlins/club.gif[/img].
UTG calls t100, MP calls t100, <font color="#666666">3 folds</font>, HERO checks.

Flop: (t350) 9[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">HERO bets t250</font>, UTG calls t250, MP folds.

Turn: (t850) 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
HERO checks, <font color="#CC3333">UTG bets t400</font>, HERO ???


No reads since i was multi-tabling.

i bet out w/70% pot incase he was drawing.

when he called, I put the Villian on top pair better kicker, or the 9, or the 4, or is going for the flush draw (he is the big stack).

Should i have checked on the turn?

and My next move is???

[11t]

I hate being in situations like this. I'd suggest folding on the turn and finding a better spot for your chips.

Difficult situation, I'd be more inclined to check the flop and fold to a pot sized raise. You could easily lose a lot of your chips in this hand.