$400nl: 300bb deep with top pair vs. possibly tilting villain

[snowbank]

history: I have position on villain, and have really been pushing him around all session. I've been 3 betting him a lot, and postflop bullying him pretty hard. He's been pretty passive for the most part. Here is one decent sized pot that I went to showdown with him on:

Full Tilt Poker, $2/$4 NL Hold'em Cash Game, 4 Players
LegoPoker Hand History Converter

UTG: $710
Hero (BTN): $1,694.20
SB: $134
BB: $462.20

Pre-Flop: A[img]/images/graemlins/diamond.gif[/img] J[img]/images/graemlins/heart.gif[/img] dealt to Hero (BTN)
<font color="red">UTG raises to $14</font>, <font color="red">Hero raises to $48</font>, 2 folds, UTG calls $34

Flop: ($102) T[img]/images/graemlins/diamond.gif[/img] 8[img]/images/graemlins/club.gif[/img] 2[img]/images/graemlins/club.gif[/img] (2 Players)
UTG checks, <font color="red">Hero bets $65</font>, UTG calls $65

Turn: ($232) J[img]/images/graemlins/diamond.gif[/img] (2 Players)
UTG checks, Hero checks

River: ($232) 5[img]/images/graemlins/spade.gif[/img] (2 Players)
UTG checks, <font color="red">Hero bets $155</font>, UTG calls $155

Results: $542 Pot ($2 Rake)
UTG mucked 7[img]/images/graemlins/heart.gif[/img] 7[img]/images/graemlins/diamond.gif[/img] (a pair of Sevens) and LOST (-$268 NET)
Hero showed A[img]/images/graemlins/diamond.gif[/img] J[img]/images/graemlins/heart.gif[/img] (a pair of Jacks) and WON $540 (+$272 NET)

we haven't been involved in many big pots, he usually gives it up early to me.

here's the hand:

Full Tilt Poker, $2/$4 NL Hold'em Cash Game, 6 Players
LegoPoker Hand History Converter

BB: $409.70
UTG: $400
MP: $1,232.30
Hero (CO): $2,314.90
BTN: $384
SB: $1,792.80

Pre-Flop: T[img]/images/graemlins/diamond.gif[/img] 8[img]/images/graemlins/diamond.gif[/img] dealt to Hero (CO)
UTG folds, <font color="red">MP raises to $14</font>, <font color="red">Hero raises to $48</font>, 3 folds, MP calls $34

Flop: ($102) T[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/spade.gif[/img] 2[img]/images/graemlins/club.gif[/img] (2 Players)
MP checks, <font color="red">Hero bets $65</font>, <font color="red">MP raises to $210</font>, Hero calls $145

Turn: ($522) A[img]/images/graemlins/diamond.gif[/img] (2 Players)
<font color="red">MP bets $275</font>, Hero calls $275

River: ($1,072) K[img]/images/graemlins/diamond.gif[/img] (2 Players)
MP checks, Hero ???

I think this is the first time he's raised a cbet from me. Again, he's been pretty passive, so this is unusual for him. I call because I think he's getting fed up with me pushing him around. On the turn, he bets the A, which I can't really put him on a lot here because if he did hit the turn, I really think he might check since he's been super passive so far. He could have an A if he was just making a play on the flop, but I didn't believe him. He could have a set here. The river, he checks, and I don't think he has an A here, he obv doesn't have a set now. I don't know whether I should turn my hand into a bluff, and possibly push off JJ/QQ, or check behind and hope my hand is good. Thoughts?