SB : 1.2k
UTG1 : abt 2k odd
mp:1.6k
Hero: 3.5k

5/5/10 live

utg+1 opened 35 . MP(nit reg) raises to 140. i decided to flat QcQs on the HJ. SB (fairly tight straightforward player) overcalls. inital open folded.
FLOP : 4,5,9 s s x
MP c bets 250.. i flat and SB went all in for 500 more ( 750). MP tanks and flats with abt 800 behind.
Can i justify a call or is it always auto fold in that spot.

Thank you