What did Newt's note mean to Thomas?

"KILL ME. IF YOU EVER WERE MY FRIEND, KILL ME." -Newt's note to Thomas

Newt was a Glader in the Maze before escaping with Greenie Thomas, and then Greenie #2 Teresa. They escaped the Maze. They survived the Scorch Trials. Now it's the Death Cure. Newt turns into a Crank, these mean ugly people that go insane and kill each other and eat each other after they're done killing each other.

Before Newt went to Denver, the home of the full-gone Cranks, he gives a note to Thomas and told him to read it when the time comes. The note read: "KILL ME. IF YOU WERE EVER MY FRIEND, KILL ME."

What did the note mean to Thomas? What do YOU think it means?

Then that was the end of Newt's life. After they met Lawrence, Newt told Thomas to leave and then he told Thomas to shoot him so he wouldn't be a full-gone Crank.