2/5 Max buy $200 at Commerce Casino

Situation:
SB: $600 Standard loose passive amateur, overplays premium starting hands, esp pairs and AK
BB $1200 LAG, makes a lot of fake value raise bluffs
Hero $400 Ultra tight image, which doesn't slow up the table at all
Late Position Calling Station $200

Hand:

Limped to me in early middle position with
I call.
5 limps to the SB, who raises to $35. $35 is the standard raise for a big pocket pair.
Standard no fold em hold em where very few players will raise, but most have no problem calling big raises oop.

BB calls $35, I call, CS to my left calls. 4 to the flop.

($150) Flop:

Preflop raiser smirks a little bit, then checks. BB leads out for $100.
I think about pushing here, but the smirk and the bb lead give me a bit of pause. I call with the intent to evaluate a possible push on the turn.

CS to my left calls. PF raiser check raises to $300. BB goes all in for $1100 and covers everyone.

Hero??????

I can't fold this. MALLIN. Here's hoping you were up against three FD's.

I'm going to try and guess the hand because I want to type more.

SB(PFRer) has
BB had J7.
CS had KJ.

Are you serious that it's a 2/5 200 max buy-in?! That's 40BB!

I never fold a set live unless it's something like bottom set on a 9TJ mono flop.

It's...LIVE...MALLIN