Can I raise/fold THIS river?

[PokerBob]

live game 7 handed
I have only been in the game for about 10 minutes. BB here plays a lot and has played a lot with me. He plays OK, and is likely a winner in most Canterbury games, but limps too much in EP and has a few other leaks. He also often wears sunglasses, which I emjoy, but he does not have them on tonight. I have not seen him get out of line often, and in this session I have not seen him do anything.

folds to me in the CO and I raise K [img]/images/graemlins/heart.gif[/img]8 [img]/images/graemlins/heart.gif[/img], SB folds, BB 3bets, I call.

Flop HU: J [img]/images/graemlins/diamond.gif[/img]8 [img]/images/graemlins/diamond.gif[/img]4 [img]/images/graemlins/club.gif[/img]
BB dark bets the flop, I call.

turn: 8 [img]/images/graemlins/spade.gif[/img]

BB bets, I raise, BB calls.

river: A [img]/images/graemlins/heart.gif[/img]

BB bets, can I raise/fold here?