Put the genie back in the bottle.
It isn't necessarily a good or a bad thing. The point is that something has been released, made known, made real, put into motion etc and it's not possible to reverse the process. In the example you give, the release of her talent seems like a good thing from her point of view, but a bad thing from his.
A similar phrase which means much the same is: "Now the toothpaste's out of the tube". Good or bad, there's no way it can go back in.
not a teacher
Student or Learner