Set on the river

NL400 PartyPoker.

I pick up 8[img]/images/graemlins/spade.gif[/img]8[img]/images/graemlins/club.gif[/img] UTG and open for a standard 4bb.
All folds to a reasonable BB (~385) calls. Haven't seen anything unreasonable about him in the 80 hands I've played with him.

Flop is: A[img]/images/graemlins/heart.gif[/img]Q[img]/images/graemlins/spade.gif[/img]9[img]/images/graemlins/diamond.gif[/img].
Villain checks, I make standard CB of about 80% pot. He calls.

Turn is: 5[img]/images/graemlins/club.gif[/img]
We both check.

River is: 8[img]/images/graemlins/heart.gif[/img].
I pick up the set. He bets into you for 80% pot (which is reasonable given the weakness you've shown). 69$ to call pot size is about 150$ total.

What do you do here, and why?