flopped nut straight, badly played?

[bilbo-san]

Ok, I'm pretty sure I played badly here, but I'd like to know if you all think I should fold this turn or river.

No player-specific reads but I've generally seen a lot of people betting 2nd pair (or worse) from early position on many flops.

Party Poker 0.50/1 Hold'em (10 handed)

Preflop: Hero is MP2 with K[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/club.gif[/img].
UTG calls, UTG+1 calls, UTG+2 folds, MP1 folds, Hero calls, MP3 folds, CO folds, Button folds, SB completes, BB checks.

Flop: (5 SB) T[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/spade.gif[/img], J[img]/images/graemlins/heart.gif[/img] <font color="blue">(5 players)</font>
<font color="CC3333">SB bets</font>, BB folds, UTG calls, UTG+1 calls, <font color="CC3333">Hero raises</font>, SB calls, UTG calls, UTG+1 calls.

I see no point in slow-playing as this must have hit somebody.

Turn: (6.50 BB) J[img]/images/graemlins/spade.gif[/img] <font color="blue">(4 players)</font>
<font color="CC3333">SB bets</font>, UTG folds, UTG+1 calls, <font color="CC3333">Hero raises</font>, SB calls, UTG+1 calls.

I was worried about the spade, but also didn't want to see monsters under the bed. Also, if SB has just hit trip Jacks then I'm still ahead. I've got zero outs if I'm behind, though, so I'd have to fold to a re-raise, correct?.

River: (12.50 BB) Q[img]/images/graemlins/diamond.gif[/img] <font color="blue">(3 players)</font>
SB checks, <font color="CC3333">UTG+1 bets</font>, Hero calls, <font color="CC3333">SB raises</font>, <font color="CC3333">UTG+1 3-bets</font>, Hero calls, SB calls.

At this point I was very concerned that everyone had a K I'd be folding a split hand. That was my only reasoning. I thought any flush would have re-raised the turn, as would JT and AJ. Am I being fishy?

Final Pot: 21.50 BB