What gets me is the random death at the beginning what was that all about? What was the reason? How did he just fall in love with her after seeing death???

I've seen this criticism before, and I don't understand why that needs to have a reason. It was a random death, something that happens. It's an interesting and attention grabbing anecdote used to kick the book off, that's all. Also, where was it indicated that he fell in love with her "after seeing death"? He was a fan of her writing prior to that, and they gradually fell in love with each other throughout the book.

Why was there a random sleep walking scene???? What purpose did it have in the story?

This was actually a pretty big plot point, not random at all. Lowen describes struggling with sleepwalking, it's the reason she wants a lock on her door, its the reason Jeremy installs multiple locks on her door and one on Verity's. The sleepwalking backstory set up multiple scenes in the book, and also alludes to Lowen having mental issues which makes her thoughts an accusations about Verity faking everything more questionable.

Who reads a manuscript that god damn slow JERMEY READ IT IN ONE SITTING? i mean he already knew about it but still MY GOD.

Pacing. I agree it didn't make a ton of sense that she spent three hours reading one of Verity's books and then read one chapter of the juicier manuscript - but maybe she legitimately felt like she was violating her privacy. Either way, she had to read it at that pace for the sake of the book's pacing and tension building.

I think the best plot twist would’ve been Jeremy and Rowen turning out to be the real villains.

That's exactly how the bonus chapter ended, isn't it? Jeremy literally murdered an innocent woman, Lowen knows all about it and doesn't say anything. They are villains.

There are fair criticisms to have with this book, but I feel like it gets unnecessary hate just because of its popularity. It's a fun read and keeps you guessing and engaged with the story.