How we cite our quotes: (Act.Scene.Line)
Quote #1
[…] Who must dispatch me?
I account this world a tedious theatre,
For I do play a part in't 'gainst my will. (4.1.81-82)
Meta-alert. Duchess of Malfi is known for bringing attention to its own theatricality—it's full of theatrical device and frequently features instances of the characters themselves being turned into an audience watching other characters perform.
Quote #2
I am not mad yet, to my cause of sorrow.
Th'heaven o'er my head seems made of molten brass,
The earth of flaming sulphur, yet I am not mad;
I am acquainted with sad misery
As the tanned galley-slave is with his oar. (4.2.23-28)
"Gee, I wish I were crazy" isn't something you hear much, but if you were being tormented the way the Duchess is by Ferdinand you'd probably wish you were nuts, too. Not only is earth a terrible place, but even heaven is figured as a kind of inferno—she's actually quoting a bit of the Bible talking about God's smiting methods. This is also the point at which Bosola starts undergoing a change of heart, partly because he realizes the Duchess shares his attitude about the world. The Duchess here likens herself to a galley-slave, which is exactly what Bosola was for many years as punishment for his work for the Cardinal.
Quote #3
And Fortune seems only to have her eye-sight
To behold my tragedy. (4.2.35-36)
We don't blame the Duchess for being such a Debbie Downer. After all, she's being tortured by Ferdinand, and is going to be executed in the not-to-distant future. Unlike Bosola, who ends up thinking that Fortune, if it exists, is basically random, the Duchess thinks that the deck is actually stacked against her, and, truth be told, she's kinda right.