Counterfeited 2 pair on the river, what to do?

[KaiShin]

Only my 5th hand at the table, but SB seems semi-loose preflop, aggressive postflop. Button looks like a loose-passive donk.

Party Poker 0.5/1 Hold'em (6 handed) converter

Preflop: Hero is BB with 5[img]/images/graemlins/diamond.gif[/img], J[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">2 folds</font>, CO calls, Button calls, SB completes, Hero checks.

Flop: (4 SB) J[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, CO folds, Button calls, SB calls.

<font color="blue"> No preflop raises, I think I should bet here. Can't count on someone else to bet otherwise I would try and CR. </font>

Turn: (3.50 BB) 6[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, Button calls, <font color="#CC3333">SB raises</font>, Hero calls, Button folds.

<font color="blue"> I don't want to 3-bet here cause if its capped I'm in big trouble. I figure I'll just call this and the river. </font>

River: (8.50 BB) 6[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets</font>, Hero ???

<font color="blue"> Well crap. Now there's a higher pair on the table and if SB has a J I don't think my 5 kicker will play. Would you call this here? </font>