@tired_programmer I don't think this is really the place for that. Also, everyone in this thread is giving fantastic advice and I love all of you.
I'm going to copy this comment that I wrote a few days ago where I talk about coping with imposter syndrome, since everything I said there applies. Everything here will be in the general second-person tense.
I struggle anxiety and have previously dealt with depression, so what you said definitely resonates with me. My struggles manifest a lot through negative self-talk, so thoughts like the ones you mentioned are something that I'm very familiar with.
One of the coping mechanisms I use is anthropomorphizing those thoughts. "This isn't real, this is just my brain being a jerk and telling me ugly things." It sounds silly, but I find it helpful, and it's pretty true. The only one insulting my work is the voice in my head, and that voice doesn't exist outside of the confines of my mind. Instead of being my thoughts, they become an enemy that I can fight against.
Another thing that someone taught me is to counter every self-defeating ugly thought about myself with two positive ones. That way, you can outweigh the negatives with positives. Additionally, thinking of positive things takes up the space in your head that is being used to think of negative ones. Over time, it can help form positive habits.
These are just a few of my personal coping mechanisms. Everybody has different things that work for them, and it can take some time to find what works for you. Also, I'll be the obnoxious presumptuous person who talks about how great therapy is. Therapy is great. There, I said it.
I hope this helps!
Find Healthy Coping Mechanisms that Work for YOU
Everyone has a different set of coping mechanisms that work for them, and it can take some experimentation to find what your best option is. What works for you can change over time, as well, so it's important to keep searching. Don't feel bad if your coping mechanisms are weird, as long as they are healthy. For example: When my anxiety is really bad and I am on the edge of a panic attack, I play bullet hell games on high difficulty, since they require 100% of my concentration and leave no room to think about anything that I am worried about. Your coping mechanisms can be bizarre. That's ok.
Learn How to Calm Yourself through Breathing
The only action that I can think of that is universally helpful is using breathing techniques, since those have a very direct and dramatic physiological effect on your body and brain. Definitely look up the proper techniques for breathing. This is especially helpful if you deal with anxiety or panic attacks.
Everything @NickRowler listed above is absolute gold.
Eva 1.0: You are Not Alone
Even though no one has gone through your exact experiences, there are a LOT of people out there that struggle with depression, many of whom are hiding it. No matter how alone you feel, there are others who feel similarly.
Therapy and counseling are not options available for everyone, but if they are an option for you, ABSOLUTELY take advantage of them. I'm not saying this as a psychology major, I'm saying this as someone who waited too long to go to counseling and really regrets it. There never has to be shame in asking for help, and no one is going to turn you away and tell you that you aren't depressed enough, or that it's all in your head, or something like that. Take a chance and sign up, if you can. Walking into counseling for the first time and admitting something felt wrong is literally one of the hardest things I have ever done. But it was worth it. At this point in my life, my depression hasn't gone away completely, but it has been reduced to a level where I can manage it and enjoy my life. I owe a large part of that to therapy.
Thank you so much for making this thread, Diego. To anyone out there who is struggling, I hope this helps you. <3