What is the ruling on writing sexual stories secretly that are not published, with the them being torn up after completion?

Writing and publishing erotic stories is impermissible due to the incitement of desires and the spread of indecency therein. Writing them and then destroying them before anyone sees them is less severe than publishing them, but that does not mean it is permissible. Merely conjuring sexual fantasies with a specific woman and deriving pleasure from them is impermissible, because thinking about a specific woman is a cause for temptation. However, if one thinks about this act in general, for example, imagining having intercourse with a woman and then ejaculating, there is no harm in it, along with the advice not to expose oneself to it because it is unnatural. These matters are a waste of time in that which is not beneficial.