"How do you stop yourself from obsessing over the negative?"

By getting it out of my head somehow, like talking about it over and over, crying, yelling, listening to other people who can talk me down. Feeling the emotions, like humiliation, shame, fear, whatever. Because, like you said, don't want it to become a depression. For me, that obsessive cycle can also make me lose touch with rational thought and reality.

I can identify with the pain of wondering how good a teacher you really are, and of facing how teaching in violent, chaotic schools shaped the teacher I became. My teaching career is ending this school year, after a final semester on medical leave. I'm retiring after only 17 years in the field (3rd career for me).

It sounds like you are still early in your career, and are keen to continue. I'd advise envisioning yourself in a wonderful and supportive learning environment, where everyone is encouraged to make mistakes, take risks, and have fun!!!

You'll get a great position, you are preparing for it, and they will be lucky to get you.