OMG, I think I've Lost a Ton of Money on Flush Draws

[tor]

Hero has been being nagged by girlfriend and forgot to sit out. When he comes back there are two unknowns to his right.

Hero is in the BB w/ K[img]/images/graemlins/heart.gif[/img]2[img]/images/graemlins/heart.gif[/img]
All fold to button who calls, SB folds.
Hero checks.

2.5 SB in pot.
Flop comes, 6[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/spade.gif[/img]

Hero checks, Button Bets, Hero ???

Please humor me in all my stupidity.