When I think of "letter" I think of a longer poem or anything like that. Me personally in the title I would change "letter" to "poem".

The details you show the reader are great. There is so much hint of sadness. For me the first line is great because again it pulls the reader in, not knowing where it is going. You are hiding your emotions through the second line because you don't want to show the person you care about your sadness. I like the meds line, because that proves how " sick" you are or were. But the ending holds the most emotion and there is a lot going on there. It's hard to finish the letter because you are bleeding, which tells me you are getting weaker. And soon you will pass on. Great write