I love this poem for a couple of reasons. First of all, it is incredibly expressive and relatable. Secondly, I love wintry and icy themes. There is something deep about the cold, the same way that a depression may freeze someone from living.
There were two particular lines I absolutely loved.
"Ghasts gathered in my barn brain".
The simple play of the two alliterations (if I can call them that way) is smart and leaves more impact with that imagery.
"My sadness was most happy
As I aged and truth sank in."
This was quite reflective. Sadness is not always 'bad'. Sure, it is not the most pleasant feeling. However, sadness is a necessary part of acceptance; and when there is truth behind the sadness, it is not as disturbing, it feels natural. It belongs.
And regarding the note: I agree. Write, write & write. Poetry is what got me out of my depression 4 years ago. Papers bore all those unbearable feelings that I used to have.