I was in a 2400 person online tourn. with the top 40 getting payed. I am in 11th place and there are 46 players left. The chip leader (who I suspected of stealing a lot of blinds and pots) is the SB and raises driving everyone but me out, I was in middle position. I flop a k high flush. Chip leader bets half my stack. I raise all-in. He turns over a A high flush and I am out in 46th place. I already know that I made a stupid move (I am still working on my discipline issues) but I want your opinion what you think would have been the best way to play this and when would it have been the time to fold.