I'm always unsure about river folds like this. The pot's big and I later regreted the fold. Thoughts?

READS
MP3 is unknown, only read on him is his played 3/5 hands thus far

UTG is loose/passive - 40/3/0.5 after 340 hands

Party Poker 5.00/10.00 Hold'em <font color="#0000FF">(9 handed)</font> link

Preflop: Hero is UTG+1 with J[img]/images/graemlins/diamond.gif[/img], J[img]/images/graemlins/club.gif[/img].
UTG calls, <font color="#CC3333">Hero raises</font>, <font color="#666666">2 folds</font>, MP3 calls, <font color="#666666">3 folds</font>, BB calls, UTG calls.

Flop: (8.33 SB) T[img]/images/graemlins/diamond.gif[/img], 2[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, UTG checks, <font color="#CC3333">Hero bets</font>, MP3 calls, BB calls, UTG calls.

Turn: (6.17 BB) 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, UTG checks, <font color="#CC3333">Hero bets</font>, MP3 calls, BB folds, UTG calls.

River: (9.17 BB) T[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, Hero checks, <font color="#CC3333">MP3 bets</font>, UTG calls, Hero folds.

Final Pot: 11.17 BB.