Legally speaking you need to talk to a lawyer to insure that things are legal and fine. In fact someone with experience in the fields can easily help you with that problem in one setting, afaik.
However I will got into two different things.
Through all of the history of literature and of the arts in general, works of art are for a large part repetitions of the tradition; to the entire history of artistic creativity belong plagiarism, literary theft, appropriation, incorporation, retelling, rewriting, recapitulation, revision, reprise, thematic variation, ironic retake, parody, imitation, stylistic theft, pastiches, collages, and deliberate assemblages. There is no rigorous and precise distinction between practices like imitation, stylistic plagiarism, copy, replica and forgery.These appropriation procedures are the main axis of a literate culture, in which the tradition of the canonic past is being constantly rewritten.
With that in mind: we honestly can't answering without knowing more.
The difference between stealing and being inspired is very case by case context dependent thing that I think we won't be able to give a good answer without all the facts.
Anyway I think we need to address that you might have just thought of the idea as a joke and it became real.
So. I think a vital question is: why is my thing different?
Let me give you an example. Pan's Labyrinth inspired so much that I made a short story about a girl who moves to a new place and starts thinking that she is a princess or reincarnation of a princess and that her real magical kingly parents are looking for her. She meets a nice teacher-tailor and she befriends her.
Long story short, or short story shorter, as the girls family life is in trouble the girl reads in a magical books that she needs to kill herself to return. She goes the place the books says and actually does it. The girl is found by the teacher as she is dying. A portal opens and the court wizards steps out greeting the teacher as the princess and explains that he deceived the girl to do that in order to get her to open the portal but in a specific way that even if the real princess ordered him to use his magic to save the girl he can't.
Now I'm clearly inspired by Pan's Labyrinth but I think what I did is a sort of a nice little twist to the story. A fractured fairly tale if ever was one.
That is aside from many other elements in the story and execution.
So I don't consider this stealing or that I copied or anything. The same plot, girl is magical, is very common and don't belong to one person.
I simply know for a fact that this movies moved me so much.
Same with many things. As a writer you are hit with a thing and your mind does it's one things and comes up with all sorts of twists and plots and stories about it. That's how it works.
That is why Watchmen is a masterpiece of a movie and one of the greatest deconstruction movies handling the super hero genre. Not that it stole from other stories.
Why? The tune, the deconstruction, the story, the characters...etc
So. The most important question is again: What is my work doing different?
The girl is magical and hunt monsters but falls in love with one then it sounds super boring and cliched.
But if the execution truly translates the struggle of the situation then all the other familiar elements make way to your amazing writing and brilliant execution.
Most people who pick up the book want to enjoy themselves. Even someone as critical of anything as me once he is faced with a decent story and a writer who respects me then I'm all too happy to just follow along and shut the analytical part of my brain off.
So. Basically just focus on making the execution good and try to make sure that your work stands out on it's own.
Blake Snyder famously, and correctly, said: Make it simple so that a caveman and his body can understand it.
How it is different and stands out on it's own is again too vast of a topic.