NL50: River completes FD and brings overcard, villain open pushes

[a poker student]

I'd fold. If he was bluffing he's maybe going to show his cards anyway, and I will pat him on the back.

Perhaps I would not bet on the turn. He called your flop-bet, saying he is going to call your <pot turn bet too if he is on a flush-draw. Or I would bet 1.5 pot on the turn.

Anyway I'm a newbie, so comments are welcome but don't take my line too seriously.