Hank, my god... I'm sorry.
Estrogen at the levels Trans*women need to take can damage the liver, particularly in pill form (the most common form due to low cost).
I think that doing the HIV work in her name is a perfectly wonderful way to remember this obviously amazing woman.
Take care of yourself my friend. Don't dwell on the "what if''s" or the "I should have's". She touched your life for the better, and she touched many others as well. You touched her life for the better as you touch many others.
There is no "cheer up" or kind words I can really offer that will come close to comfort. But, if you need to vent, cry, whatever ... I'm here.