I think you fold the 77 hand. I am torn, slightly, because it's $10NL, but... he called your turn bet with the only draw being the two spades, and his river bet looks like a value bet (though it could be a weak bluff). I think with 3rd pair here you're almost never good - only a lower PP or a bluff gives you a chance, and his enormous PF raise indicates he has something better than that.

If this was $50NL then his line could be a bluff or a whiffed flush draw; at $10, I think this is unlikely. If you want to play the river, make a blocking bet maybe? He'll fold if he's drawing and is only raising with a hand to which you can safely fold.