200/400 Live. Nut Flush

[amulet]

200/400 Live

Tight aggressive game with good players. In an unusual hand it was fold to me on the button with Ah9h. I raise, expert in sb calls, good player in BB calls.

Flop Kh,2d,5H.

SB leads, BB makes it 2 bets, I 3 bet, both call.
(clear to me and I think everone that SB had a smaller flush draw).

Turn Qc

both check, I check.

River Qh.

SB leads, BB raises, I.........

I believe that BB would not reraise unless he could beat a flush.

What do I do? I know what I did, but results aside, I would love feed back on all streets, especially the river.