I need help finding a fairy guide book I read when I was younger

Okay so I don’t really know if this is the right subreddit but I am kinda desperate.

When I was younger, probably around 2015-2017, I checked out this book from a library that was basically a guide to fairies. It had illustrations on it, a small key on the cover I think along with a multitude of other things. I think the base color for the cover was purple but I could be wrong.

I can’t really remember anything else in the book besides the illustration and one passage that tells you that if you encounter this one fae, you have to tell a secret no one but you knows and you will also forget it.

It a lot like How to Spot a Fairy by Sarah Glenn Marsh, but it is a different book since the one I am looking for has more illustrations and probably came out a couple years earlier.

The library I read it first from doesn’t have an online catalogue, is barely open, and when it is I have work so I can’t go check it out.

I know I didn’t give much information but I hope someone can help me find it. It would mean so much to me.