My girlfriend secretly reads spicy romance novels and I don't like it. 21M and 19F.

Do you consider reading "spicy" romance novels a red flag if youre pursuing a serious relationship? 21M and 19F.

So I just found out that my girlfriend reads a lot of romance novels and when I talk to her about it she said that she wanted to tell me earlier but she forgot. Note that we have talked about books and what we read many many times and she didn't mention this type of books even once.

The books are very porn-ish and role play-ish. Some about having s*x with some billionaire and some about cheating and having affairs with multiple men. It's all about romantic and sexual fantasies.

Her living this double world of reading these romance books as a fantasy and living with me as a reality really made me discouraged to be in such a relationship and the fact that THESE are her fantasies doesn't sit right with me at all.

I should add that I did something not nice and treated her like never before because of this:

I've brought up this topic to her sometimes and one day she brought me one of these books for me to read its first chapter while I was playing videos game(it was definitely one of the safer ones). I did read it and when she asked about my opinion I said "do you know I was this 🤏 close to break up with you because of these stupid shits you read?" and went back to my video game(as I said I've never even come close to treating her like that). She sat about 4-5 minutes and then went to the bathroom and started crying(not loud but I secretly listened). I know what I did was pretty harsh to her but that's honestly proportionate to how much I hated it.

She started laying some(safer ones) of them in her bookshelf after I knew but after this interaction she put them out again(haven't checked yet but they're probably where she was hiding them in first place) and she's acting like nothing happened. I am also not reacting right now but I just can't ignore it.

What's should I do now?

TLDR: my girlfriends reading written porn and I have a problem with that, some are about being with multiple men and cheating which makes it much worse.

I've told her that I'm was about to break up with her over them and it made her cry, I'm still strongly considering it and but I'm not sure.