My depression is depressed

I felt it in my cold damp soul

It's hard, the only person that I hold close to as a motivation to not end myself, is my beloved mother

The more dead I feel inside, the prettier I look.
Concealer hides my mental problems as it covers my dark circles.

Maybe visit your GP and ask to be tested just in case. That way you can start combating the problem early on and helping yourself get out of any negative ways of thinking with a therapist, or you could start on medication if you think that's right for you.

Good advice, but my workplace culture is not conducive to that. And there's no easy way to remove myself without ruining the rest of my life.

You can see your doctor without your workplace knowing and go to a therapist without them knowing too, it's your right to confidentiality. I don't know your exact circumstance of course but your health is top priority, most workplaces have mental health plans.