To be honest, her getting a tongue-lashing from her father is probably the worst that's gonna happen at this point. And when said dad (not sure whether he'll even feature in the story) learns his daughter's boyfriend is the star student of the police academy, he'll probably think more of how to help her tie the knot with Ji Yong than of anything else.
As for her being used… well, Ji Yong did give her a wrong phone number in the beginning so he wouldn't see her again. Any sensible person would've taken the cue that one doesn't give their own phone number wrong by accident. But she still stalked him to that bus stop, so I guess at that point Ji Yong thought, "well, why not, since she's so keen on it".
And I'll give him that: he's been a total Prince Charming to her. Girl has a fake boyfriend who treats her better than many true ones in romance webtoons.