Middle pair, big river bet

[McDirk]

Villain is running 29/11/2 over 125 hands. I've seen him make this play twice on other players: once he had the nuts, once a busted flush draw. I've got position on villain and am trying to play stack-a-donk.

50NL blinds, .25/.50
Hero ($85)
Villain ($240)

Villain (UTG) raises to $3.00
Hero calls in MP with (Td Ts)
Rest of table and blinds fold.

Flop (Jc 2c 6d)
Villain bets $8.
Hero calls $8.

Turn (2d)
Villain checks.
Hero checks.

River (9s)
Villain goes all in ($229).
Hero ???