But in that case it probably would have been much safer for her to build more than to deplete the third pile. Given that you were able to overtake from the state of "10 curses in a deck", I suppose the board actually had enough components to continue building.
Why's that? I was able to recover not through my sheer brilliance but because she gave me the time to do it. A quick ending would have left her with 1 or 2 points (from estates she had not yet trashed) and me firmly in the negatives.
I mean there are other factors (she's my wife and playing Dominion is one of our favorite things, so making the game longer is worth it) but from a purely win or lose standpoint, she should have gone for the last pile.