YOU SAID:

I am so excited for the sleepover tonight but forget a book so I thank you for lending me one

INTO JAPANESE

今夜のお泊りが楽しみだけど本を忘れたので貸してくれてありがとう

BACK INTO ENGLISH

I'm looking forward to staying tonight, but I forgot my book, so thank you for lending it to me.

INTO JAPANESE

今夜泊まるのが楽しみなのですが、本を忘れてしまったので貸してくれてありがとう。

BACK INTO ENGLISH

I'm looking forward to staying tonight, but I forgot my book, so thank you for lending it to me.