Help me on the turn

[AlmightyJay]

Table had been fairly loose and passive. My call is marginal with only one limper to me, but I figured I'd have position and expected both blinds to play. No solid read on villian here; I only have around ten hands with him.

On the flop I've got top pair with two backdoor draws, I think this is a standard bet when checked to. But then a K drops and I get donked. What do you do here?

Party Poker 1/2 Hold'em (9 max, 8 handed) FTR converter on zerodivide.cx

Preflop: Hero is Button with 9[img]/images/graemlins/club.gif[/img], 8[img]/images/graemlins/club.gif[/img].
<font color="#666666">2 folds</font>, MP1 calls, <font color="#666666">2 folds</font>, Hero calls, <font color="#666666">1 fold</font>, BB checks.

Flop: (3.50 SB) 8[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/club.gif[/img], 2[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, MP1 checks, <font color="#CC3333">Hero bets</font>, BB folds, MP1 calls.

Turn: (2.75 BB) K[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">MP1 bets</font>, <font color="blue">Hero...</font>