another "big pot/ should I pay off?" question

[mathman711777]

6/12 BM

I have 9 [img]/images/graemlins/spade.gif[/img]9 [img]/images/graemlins/diamond.gif[/img] on button with 6 opponents and I raised and they all called

Flop: 9 [img]/images/graemlins/heart.gif[/img]8 [img]/images/graemlins/diamond.gif[/img]2 [img]/images/graemlins/club.gif[/img] they all check, I bet, they all call

Turn: T [img]/images/graemlins/diamond.gif[/img] they all check, I bet get 4 calls

River J [img]/images/graemlins/diamond.gif[/img] UTG bets into me and all fold to me, so now there are 17BB in. UTG is loose-passive so his bet indicates just about a guaranteed straight or flush, but I must call as the pot is huge....or must I?

Comments appreciated.