board shows nut straight, opponent all-in

HERO holds 2[img]/images/graemlins/spade.gif[/img],K[img]/images/graemlins/spade.gif[/img]

PRE-FLOP
Four limpers, plus SB, and BB.

FLOP [board cards Q[img]/images/graemlins/heart.gif[/img],A[img]/images/graemlins/club.gif[/img],10[img]/images/graemlins/heart.gif[/img]]
SB bets $0.50, BB folds, UTG calls, HERO calls, Rest fold.

TURN [board cards Q[img]/images/graemlins/heart.gif[/img],A[img]/images/graemlins/club.gif[/img],10[img]/images/graemlins/heart.gif[/img],J[img]/images/graemlins/club.gif[/img] ]
SB bets $0.50, UTG calls, HERO bets $5, SB calls $4.50, UTG folds.

RIVER [board cards Q[img]/images/graemlins/heart.gif[/img],A[img]/images/graemlins/club.gif[/img],10[img]/images/graemlins/heart.gif[/img],J[img]/images/graemlins/club.gif[/img],K[img]/images/graemlins/club.gif[/img] ]
SB bets $43.40 and is all-in, Hero folds.

I am correct in folding here, right? At best I split and there is non-zero probability of a runner runner flush (or even straight flush).