400NL - villain takes a monster line, call anyways?

[Mossberg]

I'm just moving up to 400, and I feel like I'm probably folding more often than I should be (partly scared of the money, partly not used to the increased aggression).

villain is a 42/6.5/1.3 over 200 hands. I've been isolating him a fair amount (playing a solid 20/16/4 game), and he's generally been playing straightforward and somewhat passive. He makes stupid-light calldowns, but I haven't seen him get out of line wrt bluffing. I should also mention that big pairs are definitely in his range. Also, I feel like almost every time a donk makes a really weak turn bet, and then follows up with a strong river bet, it's usually a monster - yea?

Blinds: $2/$4
4 players
Converter

Stack sizes:
UTG: $396.00
Button: $529.25
Hero: $538.30
BB: $1.263.25

Pre-flop: (4 players) Hero is SB with T[img]/images/graemlins/diamond.gif[/img] T[img]/images/graemlins/club.gif[/img]
UTG folds, Button calls, <font color="#cc0000">Hero raises to $18</font>, BB folds, Button calls.

Flop: 8[img]/images/graemlins/heart.gif[/img] 7[img]/images/graemlins/club.gif[/img] 5[img]/images/graemlins/diamond.gif[/img] ($40, 2 players)
<font color="#cc0000">Hero bets $33</font>, <font color="#cc0000">Button raises to $66</font>, Hero calls.

Turn: 2[img]/images/graemlins/spade.gif[/img] ($172, 2 players)
Hero checks, <font color="#cc0000">Button bets $75</font>, Hero calls.

River: 5[img]/images/graemlins/spade.gif[/img] ($322, 2 players)
Hero checks, <font color="#cc0000">Button bets $250</font>, Hero folds.