It seems to be how depression works. It tells you how worthless you are. How you don't deserve anything. How nobody loves you. And then your true self will say, but I have people that love me. I am not worthless. Every day is a struggle with the evil me.
Some tips I read:
1) Love yourself and treat yourself as you would a best friend going through the same issue
2) Talk back to the negative voice. Question it's motives. Tell it how wrong it is. Find evidence that will prove it wrong and believe in yourself.
3) Learn to accept who you are. That you are human and will make mistakes.
4) Start a journal. Write down what you feel. Just write what comes into your head. Writing it down helps give structure to the thoughts especially when ruminating.

It is a battle. And it is hard. But this too shall pass. And on days where you are too tired to fight the battle, turn to those that love and understand you. Turn to this community. Do not fight it alone. Use all the resources available to you.

Who honors those we love for the very life we live? Who sends monsters to kill us, and at the same time sings that we will never die? Who teaches us what's real and how to laugh at lies? Who decides why we live and what we'll die to defend? Who chains us? And Who holds the key that can set us free... It's You. You have all the weapons you need. Now Fight! - Suckerpunch