Note: you focused a lot on his eyes. It was repetitive.

Not really sure HOW they broke up, and her feelings are all over the place. She is missing him, but has no regrets, but wants to join him..

So much emotion, description, and good flow, but it swallows the meaning up and hides it.

I AM REALLY TIRED.
:P
Ok.
This is a dupe.
I knew it from the start but I thought, God damn it, it’s 1 in the morning and you’ve just worked eleven hours straight but Inky, you will write.
AH WELL!
This is what Creative Writing degrees are for. Aha!

I love it!! The third paragraph, “Even now I, as I remember…” might want to tweek it. I think you may have meant, “Even now as I remember…”
But I love it! I think she killed him and is contemplating joining him soon. I guess that is one way to make sure they never leave. ;)

The wee morning hours are my favorite time to write. The brain is tired enough to stay out of the way. This is a very honest and thought-provoking letter, which illustrates how mixed up our emotions really are on the inside.

So, she killed him and expects to die. Definitely a dark little missive to a friend who is gone. Nicely done overall and congrats on pursuing that degree!