See both a psychiatrist and a therapist. Therapy like Cognitive Behavioral Therapy can give you some strategies that will help you recognize how you are feeling and give you some distance from your thoughts. For a rough example: Instead of just feeling like you’re failing, you might say, “I am having the thought that I am failing,” and that little bit of distance gives you the space to ask where the thought is coming from. You may then be able to refute it or accept it as the way you feel right now, but not necessarily who you are.
Psychiatry can help you identify if a medication may be a good option for you and what route to take with it. This will likely be a few months of trying different doses and different medications while you may journal to track the quality of your days.
If you find yourself having even brief, passive, non-planning suicidal or violent thoughts, get with a professional. They’re good at that stuff.
Once the major stuff is taken care of, it’s much easier to work on the normal things like daily exercise, nutrition, and social connections.
Not OP, but most of what I watch is on Youtube as well except for Lindsay Ellis and The Great War.
Slightly defunct with good backlogs: