Do you think you've done enough?

Yes, send her on her way

You spend a few minutes comforting the impressionable young woman, telling her that you don't think any less of her for her unfortunate infatuation, but making it clear that there can never be anything more between you than supervisor and student. Of course, at this university, that means using her as your personal maid once every few weeks and training her to please you sexually under constant threat of chastisement, but somehow, that seems less exploitative than taking advantage of her crush.

You don't know whether you've entirely succeeded in preventing her amorous interest, but by the time she leaves she is at least putting a brave face on it and you're still flattered by her attention, even if it was unwanted.