Flopped nuts, put myself in a gross spot on the river

[burningyen]

Bodog $109 tonight, t15/30 level.

Villain is unknown (2nd hand he's been at the table). I have t3170, he has t3195.

Pre-flop: Hero is dealt 9[img]/images/graemlins/diamond.gif[/img] 7[img]/images/graemlins/heart.gif[/img]

UTG goes all-in for t80, UTG+1 calls, Villain calls, 5 folds, Hero calls t50 in the BB.

Flop (t335): T[img]/images/graemlins/heart.gif[/img] 8[img]/images/graemlins/spade.gif[/img] 6[img]/images/graemlins/club.gif[/img]
Hero checks, UTG+1 checks, Villain bets t220, Hero calls, UTG+1 calls.

Turn (t335 main pot, t660 side pot): 4[img]/images/graemlins/spade.gif[/img]
Hero bets t450 (underbet due to misreading the pot amount!), UTG+1 folds, Villain tanks 10 secs and calls.

River (t335 main pot, t1560 main pot): K[img]/images/graemlins/spade.gif[/img]
Hero bets t1000, Villain insta-shoves for t1420 more.

Pot = (t335 main pot, t3980)

Hero ?

Also, comments on other streets would be appreciated.