Ryan Routh Wrote A Letter BEFORE Assassination Attempt and Already Knew He Failed?!

So Ryan Routh was traveling the world appearing in Azov Battalion commercials, recruiting for Ukraine, waiting in a bush to assassinate Trump but he wrote a letter saying he failed before he actually did the attempt? When did he write this letter, I'm confused? He wrote a letter saying he failed before he even attempted to do this? This isn't making any sense unless it's some kind of message to other assets to complete what he wasn't able to do? Where would he even get 150 thousand dollars? From Ukraine?
(Apparently he had these letters in waiting that he pre wrote. Regardless, where would he even having this kind of money and now the doj is releasing these letters, why?)