[tyler_cracker]

This is tough without reads, but MP1 could be betting a draw or a smaller pocket pair. I agree that you should raise or fold, and raising is reasonable on the flop. Folding is ok too without a read.

I would take a free turn, though, especially after everyone called your flop raise. You can then think about calling to snap off a bluff on a safe river card.

Obviously, that river card is not safe. Good fold.