UB 1-2NL NFD + Gutter

[cjp010]

UB 1-2NL

Dealt A [img]/images/graemlins/spade.gif[/img] 9 [img]/images/graemlins/spade.gif[/img] on BTN and I raise 2 -> 7, called by SB and BB.
Flop comes 5 [img]/images/graemlins/diamond.gif[/img] 6 [img]/images/graemlins/spade.gif[/img] 8 [img]/images/graemlins/spade.gif[/img],
SB/BB both Check I bet 20, SB raises to 45 BB makes it 100
I shove for 200 total, SB folds BB calls.
I've got NFD with gutshot, cards run K 2 i think club and heart and he takes it down with 77 which means my A was live and his own 7 was my gutshot. I'm not sure how you call off 200 chips with his open ender and a pair that might easily not be good, so i'm curious as to if I played this that bad or not?