Hey I'm sorry you didn't get the job but I think you're dealing with non-stuttering issue. I know what it's like to sell yourself short before you start and to feel worthless. You sound like you are in a bad place and need support. That might include therapy and medication. Additionally we live in a capitalist nightmare and getting hired is a terrible crapshoot. The job market does it's best to devalue and break us down. We need to do our best to identify and prevent this. You're not your stutter and you're not your job. There are plenty of opportunities where you will thrive, we just live in world with a stupid demoralizing process of finding them and you're not alone.