Struggling with mood, feeling overwhelmed by emotions.

I’m struggling with my mood lately.
I’m so cranky and angry at the world. It feels like depression is trying so hard to creep in and set up a tent in my subconscious mind. I’m trying hard not to let. But in the process I feel so angry.
Maybe the depression has set up camp- and the anger is my defense mechanism to prevent me from hating myself and feeling incredibly sad all the time.
All I know is that I’m feeling so extremely moody. I want to scream and cry and I’m avoiding the horrible thoughts for now - but I’m not too proud of the thoughts I get in the meantime but they’re better than the alternative.
Mostly they’re about hating other humans, hating the world, feeling cast out, feeling excluded, feeling disconnected- etc.
I *should* be feeling certain ways - excited, proud, whatever else - for the birth of my new daughter soon. But I’m not. I dread it. I’m feeling defeated, I’m feeling neglected, I’m feeling hurt, I’m feeling as if I mean nothing more than the baby and giving birth. All too familiar feelings.
I know I will love this baby with all I am. Nothing could ever change that. I’ll be the best mother I can be and I’ll continuously aim to be better - to do better, to evolve as a mother and person. My kids are my whole life. And honestly - they’re all I am. They love and care about me more than anyone else ever possibly could.
What I know and how I feel are completely different things.
And what I feel is quite overwhelming.