[UMG] How to find where the text wraps?

I have a large amount a text I would like to put on an in-game book with scalable text. Imagine a book that is open showing both pages and it shows text on the left page and then continues that text on the right page. Currently, I have a desired text size and from that I read in say, 30 lines of text from my large text file. This works great, but I want the player to be able to dynamically scale the text on the book.

The problem is, when I scale the text, I don’t know how many lines to read onto the left page before stopping and continuing the text on the right page. I’d like this to be able to work with any text, not just fixed width text.

Does anyone know how I can accomplish this?

Thanks!