Most fantasies sound weird when written or uttered.
But as long as no-one is hurt, and consenting adults are involved, you have every right to your fantasy, and whether you decide to realise it or not.
Not every fantasy needs to be acted out, some might just be too uncomfortably awkward, or painful, or even hazardous (particularly if strangers are involved).
So it’s fine for that fantasy to remain in your imagination, to be expressed in whatever why you feel comfortable. For many it’s the scenes they imagine as they masturbate, or the stories or flirtatious messages they write.
There is an element of selfishness in every fantasy, because it’s so personal to the owner. But the wonderful thing about human sexuality is that it isn’t a zero-sum game, where somebody wins and somebody loses.
Wonderfully, the chances are that there are many others out there in this huge complex world who share the counterpoint of your own fantasy. Lovely people who don’t consider your desire selfish, but who’ve been yearning to finding kindred kinky minds like you all this time…