I do think you should split this one up into 2. You should aim for around 10.000 words max, give or take 2000.

I came several times... My dick looks like a split hotdog, and I can lift a car with one hand

Cadance howled, the constant assault on her ass making it almost impossible to think at all. Drunk on sensation, she slurred out, "Yes I'm a whore yes yes I'm a fucking bitch yes please don't stop I love this please fuck me stars yes please oh please please I'm a dirty dumb whore please my King please fuc-"

I'm not entirely understanding why she is asking him not to stop. Wouldn't she want him to stop and stick his dick in her?

I also think just a touch more gentleness in several places might help it be more effective. That he rewards her for very minor good deeds. That if she does submit she will be treated well. That does goes down to even a single submissive word being rewarded with a single stroke on her back.

First: I love how she essentially just turned ff Shinings filter. He was just so frustrated and done with her BS and that spell finaly let that all come out.

Second: the way she basically hypnotized herslef by trying to fight back was..... truely beautiful. I wish I'd see that more in other stories.

Third: is it weird that I wanna know in more detail what is going on with Celestia, Luna and Twilight?^^

And because you understand what you did wrong,

11048710
That one's actually not a typo.

What do you want me to be?

Edit 12/20/2021:

Cadance waited in silence, shivering with tormented arousal.

until he reached her mouth,

as a small line of it dribbled down from the corner and onto her cheek.