There's no point in going on. But obviously you aren't quite convinced of this, since you have read this far. Severe depression has physiological causes and requires professional attention. Please seek it. I am not a trained therapist, only someone who has slogged through the swamp of depression and survived, thanks to the guidance and support of the Lord. But my depression was only borderlline, brought on by severe disappointments. Here are the prayers and the cognitive techniques that have helped this particular person.
You are my strength and my courage;
Why should I fear defeat?
You are my portion and my cup;
Why should I feel deprived?
You will never forsake me;
Why should I feel deserted?
In your image and likeness you made me;
Why should I feel deficient?
Before continuing, you may find it helpful to read about Breathing in the Lord. The deep breathing technique discussed on that page may help you use the above prayer and those which follow to lessen tension and irritability.
Most holy and adorable trinity,
one God in three persons,
I praise you and give you thanks
For all the favors you have done for me.
Your goodness has preserved me until now.
I offer you my whole being,
And in particular
The strength to keep going despite all failures and all frustrations;
All the joys and accomplishments;
(here add the good things that ARE happening.)
That I shall experience this day.
Give them your blessing.
May your divine love animate them,
And may they help reveal you to the world.
Father, I give you thanks for this food
But most of all for sending your only son,
That we might not perish,
But might have eternal life.
Bless this food, that it may strengthen me
To keep going despite all failures and all frustrations;
And to do whatever is possible
To make good things happen;
(Here add the good things that ARE happening.)
And to turn all the good things that do happen
Towards your kingdom and your holiness,
Trusting that you will do the impossible
When it is necessary and at the right time.
And will turn even the bad things to good;
Through Jesus Christ, my God and my brother.
Father, I give you thanks for
(Here add the good thing.)
But most of all for sending your only son
that we might not perish,
but might have eternal life,
a gift which nothing bad can ever outweigh,
And which shows that you will bring good even out of the worst evils.