1st hand of $109 - what the hell do you do?

[RevAgain]

Party $109:

Very first hand I am dealt KhQs in the CO and after several calls I call too, 7 see the flop including the button and both blinds.

* Dealing Flop ** [ 2h, Qh, 5h ]

It's checked to me and I bet out 125, basically the pot, and get called by the only person to act after me, the button. Everyone else folds.

Turn is Tc and I bet 225, button shoves for 860 total, first hand so obviously his stack is same as mine and I'm bust if I call and lose.

I am simply stumped here, I have top pair but against a huge starting field, although I have a redraw to the second nut flush, with only one card to come. If I'm losing to the made flush my chances of redrawing to my king are much reduced as two hearts are gone already.

I can see arguments for changing my play on preflop and flop, and was very unsure what to do on the turn.

Thoughts?