Second pair and nut flush draw OOP

[Hollywade]

I'm mostly just interested in how to play this river, but feel free to comment on other streets as well.

I have a little history with the opponent. It started when I raised with AK and he called. Flop was K-K-6 with 2 clubs. I bet, he called. Turn was a 7. I bet again and he folded. A couple hands later I raised and he called. A couple other people called behind him and I gave up on the flop.

This was the third time in the span of about 5 to 10 minutes that he called my preflop raise. I sort of had a feeling he was trying to get me back for the AK hand. Of course, this is just a hunch. Maybe he's just a calling station in general. Who knows?

I bet about 2/3 of the pot on the flop, hoping he was the type to insta-donk min-raise, in which case I would come right back over the top. When he called I was assuming an ace, straight draw, or flush draw.

Admittedly, I didn't feel very confident about my bet on the turn. I felt there was a very good chance that I still had the best hand, but for some reason I was afraid of pot-betting and having him shove. Needless to say, I was not feeling great about my idea of how to play the hand on the turn.

The river is my biggest question. If I check, it gives him a chance to bluff, but it's not likely to be a huge bet. If I bet, he is probably not going to fold an ace. He might pay me off with J10 or QJ. In retrospect, I think maybe betting was the appropriate move.

Thoughts?

Full Tilt Poker, NL Hold'em Tournament, 20/40 Blinds, 9 Players
LeggoPoker.com - Hand History Converter

SB: 3,050
BB: 3,260
UTG: 3,485
Hero (UTG+1): 3,520
UTG+2: 4,560
MP1: 2,845
MP2: 2,105
CO: 6,200
BTN: 3,960

Pre-Flop: (60) J[img]/images/graemlins/diamond.gif[/img] K[img]/images/graemlins/diamond.gif[/img] dealt to Hero (UTG+1)
UTG folds, <font color="red">Hero raises to 125</font>, 2 folds, MP2 calls 125, 4 folds

Flop: (310) A[img]/images/graemlins/diamond.gif[/img] J[img]/images/graemlins/heart.gif[/img] 3[img]/images/graemlins/diamond.gif[/img] (2 Players)
<font color="red">Hero bets 200</font>, MP2 calls 200

Turn: (710) 6[img]/images/graemlins/club.gif[/img] (2 Players)
<font color="red">Hero bets 400</font>, MP2 calls 400

River: (1,510) 5[img]/images/graemlins/heart.gif[/img] (2 Players)
Hero checks, <font color="red">MP2 bets 600</font>, Hero calls 600

Results: 2,710 Pot