Help please... (No reads on opp)

So I hit the flop and bet it OOP. Facing a substantial re-raise - how do I find out where I am at - or do I just lay it down? Calling doesn't tell me anything I think and re-raising will be very expensive.

Looking back now however it seems the only hands I beat are a LAG bluff or pocket pair who thinks I am c-betting. I guess you have to put him on KK or AA but should I really let him push me off the flop I wanted with just one re-raise in position?

Is the price of a re-raise by me worth it to make sure I am beat or just lay down the TPTK? A re-raise here by me will often take the pot down when I make it clear I am serious - but the last thing I want is to play a big pot with a small hand...

Paradise Poker No-Limit Hold'em, $0.50 BB (9 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

saw flop|saw showdown

SB ($117.45)
BB ($100.00)
UTG ($118.00)
Hero ($108.40)
MP1 ($97.50)
MP2 ($99.00)
MP3 ($117.50)
CO ($281.90)
Button ($129.30)

Preflop: Hero is UTG+1 with A, Q. SB posts a blind of $0.50.
1 fold, Hero raises to $3.5, 1 fold, MP2 calls $3.50, 5 folds.

Flop: ($8.50) Q, 2, 2 (2 players)
Hero bets $4, MP2 raises to $18, Hero ??????