This is from the song Rise Against – Savior:
It kills me not to know this, but I’ve all but just forgotten …
I am curious, is it some colloquial phrase, or is meaningless.
Answer
It means that he has almost completely forgotten.
all but:
very nearly
Source: Merriam-Webster’s Learner’s Dictionary
Attribution
Source : Link , Question Author : Mikhail Genkin , Answer Author : Reubend
