Live 100NL - Turned the nuts, fold the river?

[Russ M.]

Hero has ~$100. Villain is an idiot unthinking player. There are several maniacs at the table and extreme calling stations.

Couple of limpers, Hero limps MP w/JTo. Limped around. 6-handed flop.

Flop: K-Q-4r

Checked to Hero, this is a check right? Checked around.

Turn: Ac, two clubs on board

Loose-passive donks out $10. One caller. Hero raises to $30. Too small here? Folds to original bettor who calls. Other caller calls and then shows his hand to his neighbor who remarks "Oh, you gotta call that, you've got plenty of outs."

River: Rag of clubs

First player checks, middle player bets $40. I don't think the turn talk was an act. Can I fold this?