I found his goodbye letter!

I was down in the cellar looking for some heavy duty tape. I spotted an envelope in one of his cupboards, that I'd written on. I had a look inside and it had a handful of things & letters that I'd sent him on his last tour.
But one envelope in there had my name on it and it was still sealed... Well as it was addressed to me I decided to open it, but as I was doing it, I realised why I'd never got the letter.
I took a quick peak because I was too scared to pull out the whole letter. I just spotted "I'm sorry you've got this letter", and in big letters "THE THING WE NEVER THINK ABOUT".
My heart skipped a beat, it was the 'Final Letter' from his last tour. I froze and didn't know what to do with it, I panicked that I'd found it.. like I'd be tempting fate. I didn't know whether to bin it or what... I just put the envelope back in with all the other bits, threw it into the cupboard and came back upstairs. I feel like I can't throw it away while he is gone, but he'll have to dispose of it when he gets back, it's just too morbid knowing it's there.