Shall I fold my second nut flush on the turn facing a 2.5x pot jam?

Hero moved to this £1/£2 table for just half an hour; hero was the chip leader here with £900+, mostly from the money made at an other table earlier.

Hero opened to £10 with Q♣J♣ from UTG.
CO called (second biggest stack at the table),
Button called,
SB folded,
BB called (short stacked).

Four way to see the flop (pot was £41）
Flop: K♣6♣7♠
BB checked.
Hero bet £20.
CO called.
BTN called.
BB called.
Now we built the pot up to £121.

Limited background info for CO, BTN & BB:
V1 at CO:
Asian, female, early 30s.
Probably one of the recreational players who plays 1/w. No hand history before but the face looked familiar.
VPIP rate very low in the last half an hour since hero sat down.
In memory 0 limping in the last half an hr.
stack £400+

V2 at BTN
White, young, early 20s.
Never seen him before.
VPIP rate also on the low side but he limps.
No hand history before.
Stack 300+

V3 at BB
White, 50s, very talkative.
Loose passive.
Short stacked.

Turn was 7♣，which seemed to improve everyone's hand.
BB jammed for just £25.
Hero was thinking about whether to call or raise; hero decided to flat call.
Then we saw CO (v1) thinking for quite a while, then she said all-in, which is around £420 into the existing pot of £171.
BTN folded.
Decision on hero, hero?