how should i have played this hand

[jayo 0]

This is my first post , only playing texas holdem for about 6 months so i will try to explain this as accurate as possible:playing a $50 tourney there was 4 players left ,blinds were 200-400, chips were fairly even , i was third in chip stack , i was on big blind dealt 6s8c . Noone raised so i checked, 3 players involved. flop was 5d 7h 9d . as u can see i hit my straight , sb checked , i checked dealer position raised i think 1200, sb re raised all in , at this stage i am thinking sb has diasmond flush draw , first raiser has open ended straight , after a lot of thought i call the allin ,as does the first raiser .cards turn overas followssb pocket 7s me a straightdealer pos Ad JdIn the end the turn gave dealer a flush and river gave sb a house and knocked both of us out .if i was last to act and both went all in i would still proably have called . i am just wondering should i have folded assuming that one of these plaers was drawing and that if he hit i was out .