Sexual fantasy meaning?

So.. only recently has it come up in conversation about sexual fantasy. Like the type you don't tell people cause your scared of judgement.. you don't know what it means etc etc...

Well my husband pretty much guessed mine but i did not deny nor admit to it because I myself am disgusted in it and don't know why I get turned on by it.

Now I use the word fantasy loosely. I know that most people "fantasy" is something they want to do.. or will do.. but mine is literally so strange that I disgust myself.. before i say what it is i need to just clarify that i do not want this to happen, i do not wish for it or anything like that. It's just something that for some reason turns me on, I've watched porn about it and it's just been a big secret of mine for 2 or 3 years. But the "fantasy" is father and daughter, or brother and sister, now.. I just have to say that I have never met my father, grew up with just me and my mum. I do not have a brother. So I do not have any fantasies about specific people! But its the "idea" of it. The whole daddy thing. I dont know why!! I'm so grossed out by it. I've had aniexty over it for hours because I think my husband knows and is against it and judges me.. he told me that he would do anything except roleplay incest, he said he has one experience where a girl called him daddy and he hated it. I told him I myself would never want to roleplay it.. or want to do it.. it's just something that turns me on and I watched porn about it etc etc...

Basically i wanna know if I'm alone? I already know its messed up and I'm strange so please dont be to harsh.. I read online there is something behind our fantasy and that it's not so much, you want to fuck your dad... it's the feelings behind it.. for example, secretse, forbidden, wrong, trusted.. whatever..

I want to know why I'm drawn to it as a turn on so I can fulfill the turn on in other ways and let go of this messed up fantasy.