I have Flush, villain bets 1/2 pot on river, do I raise for value ?

Preflop is kind of ugly, but BTN and SB are real fishy. SB would raise nearly any 2 cards preflop, and BTN is a huge calling station, I was almost sure that by limping I would get a multiway pot with position to SB. BB is 22/15/2.6, but he was also playing more passively due to the table dynamics. I was playing 19/13/2 and had a weak tight image at the table.

Comments on all streets appreciated.

PokerStars No-Limit Hold'em, $1.00 BB (5 handed) Poker Stars Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

saw flop|<font color="#C00000">saw showdown</font>

<font color="#C00000">BB ($159.25)</font>
<font color="#C00000">Hero ($634.75)</font>
MP ($61.70)
Button ($46.40)
SB ($195.90)

Preflop: Hero is UTG with 7[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/spade.gif[/img].
Hero calls $1, MP calls $1, Button calls $1, SB completes, <font color="#CC3333">BB raises to $5.5</font>, Hero calls $4.50, MP calls $4.50, Button folds, SB folds.

Flop: ($18.50) 2[img]/images/graemlins/spade.gif[/img], 7[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">BB bets $10.25</font>, Hero calls $10.25, MP folds.

Turn: ($39) 5[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, <font color="#CC3333">Hero bets $23</font>, BB calls $23.

River: ($85) 2[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets $45</font>, <font color="#CC3333">

Hero ??