Captain2 - thanks for your kind words.
I built up an intellectual understanding of suicide as a Samartian for three years.
I then experienced the concept up close and personal after a complete nervous breakdown and three months in a psychiatric ward.
So I do know of what I speak, and my mental health has been hard won.
I think your phrase 'fighting depression' is absolutely appropriate - the daily struggle against the sheer negativity of every thought is utterly exhausting, hence the lethargy that usually accompanies the condition.
The mood swings, the temper, the hostility and apparently deliberate attempts to hurt and drive away the people closest to the depressive are also typical - if you hate yourself to that level, you can't imagine being worthy of the love and support of anyoneone else, so you spend what little energy you have trying to make them hate you as much as you hate yourself.
I wish your loved one every good wish with their demons, you can get past it and live again, you can get your personality back, I feel for you and your helpless feelings and inability to do anything practical.
Your support will win in the end - it is appreciated by your loved one - think of their bad behaviour as that of a drunk - you know you are behaving badly, but you can't stop yourself doing it, and you do regret it, but lack the communication skills to convey that.
Hope this helps.