Early levels $55 buyin MiniECOOP, we turn a monster..now what?

[Poker Orifice]

Another kinda interesting spot.

Reads on villain - they're an MTT reg., playing mid-high buyins and VERY aggressive.

Here's an interesting spot in a MiniECOOP tournament on Titan. Buyin I believe was either $33 or $55 and there was a HUGE overlay in the tournament (biggest I've seen in a long, long time!!).
It's very early levels and we've all started with 5,000chipstacks. Blind structure is fairly slow so there'll be lots of time to play in this.
villain in hand 'avrilpoker' is a Tourney Reg. but we've also already seen them make a couple of HUGE overshoves (so this one isn't something new for them on this table).
10-handed tables 10/20
We're dealt AhQh in UTG1 and come in with a raise of 4bb to 80.
CO, BTN, & BB all calls 320 in the pot (4-way)
Flop Qd-5h-9s
BB - checks
We lead out 'POT' 320
CO - calls 320
BB - calls 320
Turn (1,360) Qd-5h-9s "8h" (we turn the NutFlushDraw on top of our TPTK)
BB - checks
We check (in hopes of either 'check-raising' or check-calling, depending upon action.. we obviously don't want to get raised off of our draw & it's early still & we're very deepstacked)
CO leads out '525'
BB check-Raises allin 5,350
HERO: ????? (can we fold this here?)

[Poker Orifice]

I'll post the screenshot of the hand after a bit (as it'll give away what happens on the turn & don't want to give away any more info. (will post it later on though)