10-20 NL Bellagio Hand

[Xelent]

Hero($1800) raises to $80 with AKo and I get one caller($2-3K?) He has position on me and he looks kind of familiar, but I do not know much of his play yet. Flop comes 3 [img]/images/graemlins/diamond.gif[/img]8 [img]/images/graemlins/spade.gif[/img]9 [img]/images/graemlins/diamond.gif[/img]. Pot is $190 and I take a stab and bet $100. He called and I was almost positive he had the nut diamond draw based on his actions. The pot was now $390 so it was worth taking if the diamond didn't come on the turn. The turn came a J [img]/images/graemlins/heart.gif[/img]. I bet $400 (mistake?) He thinks for a little and calls. River comes a low blank card. This is a big pot and I feel like I need to bet if I want it because he probably had a pair to go along with his flush draw. I was thinking maybe he flopped it with A [img]/images/graemlins/diamond.gif[/img]8 [img]/images/graemlins/diamond.gif[/img] and a bet could take it. How should I proceed from here? Cut my losses or bet and if so, how much?