very tough spot with flopped set

[TheCount212]

I love the limp PF with 33.
You got lucky and flopped your set but got unlucky because a loose passive villain 3-bangs you on a flush board. If he's really passive (and he seems like it given your history with him) I don't think there's any way he 3bangs this flop with another set or two pair. Live, the passives I play with crap their panties on a flush board unless they've flopped it. Given your read I think he flopped his flush and, with the action in front, he's decided to take the pot right now.
I trust my read here.. call the flop raise and check/fold if you don't turn quads or a boat.. unless you're feeling lucky and want to see the river.