Turned straight on paired board

[PokerBob]

villain is an unknown.

Party Poker 3/6 Hold'em (10 handed) converter

Preflop: Hero is BB with 5[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/club.gif[/img].
<font color="#666666">1 fold</font>, UTG+1 calls, <font color="#666666">1 fold</font>, MP1 calls, <font color="#666666">1 fold</font>, MP3 calls, <font color="#666666">1 fold</font>, Button calls, SB completes, Hero checks.

Flop: (6 SB) 8[img]/images/graemlins/club.gif[/img], 6[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(6 players)</font>
SB checks, Hero checks, UTG+1 checks, MP1 checks, MP3 checks, Button checks.

Turn: (3 BB) 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(6 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, UTG+1 calls, MP1 folds, <font color="#CC3333">MP3 raises</font>, Button folds, SB folds, <font color="#CC3333">Hero 3-bets</font>, UTG+1 folds, <font color="#CC3333">MP3 caps</font>, Hero calls.

River: (12 BB) 4[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">MP3 bets</font>, Hero ???now WTF???? will it ever end for me???