I really feel for you, and i have had the same experience, but people think depression is when someone is sad but in actual fact its a illness.

From experience, and by no means am saying i am correct or this is factually scientifically proven,
but having someone near with depression, is a disease/illness, and its seriously hard to get it right.

You cannot just cheer them up by taking them to weekly remedial massages, or go to a cheer up event every day its not going to work.

Listening to your background story, I can link few common things to my past experience.

It sounds like your friend had a vision and a will do make things happen, go forward with developing herself and her life here in Australia. I can say that she would have been a very motivated, someone who will never hand hold her hand put for small help because she like to take care of everything herself.

What happens is that firstly, their bodies become very tired, but their minds dont know how tired the bodies are.
They are keen to keep things in order and keep pursuing their goals in their minds they are very willing, however the bodies get too tired hence causing what seems like a chemical imbalance.

I think the mind being so anxious but body becoming too tired must cause some kind of chemical imbalance, and thats when depression starts.

They then fall into a very nasty state where they cannot move, their heart beat rapidly, and practically become immovable, feel lock in a coffin and depressed.

Sometimes, they feel locked in a coffin, sometime they feel helpless, and sometime they are afraid to lose everything they achieved, because of their condition becoming worse and worse.

Its a very serious illness, and trying to help is hard, as the individual have to really take it on themselves.
Doing pilates, and whatever relaxes them, and stop thinking about, what they have to do this and have to do that.

i know its not a help, but i wrote this to maybe share some background insight from experience on the sad situation your in.

Not nice to hear and write about this on such a early morning.