My boss at work. Am I over-reacting? Please Help.?

Your reaction is expected based on the criticism you are getting for the job you are doing. It is obvious you are not very interested in doing the job you are interning. You need to find a line of work that lets you concentrate on your work and keep you focused. The job is boring to you and your mind is elsewhere causing you to forget and make obvious mistakes. For your happiness and for your boss's happiness, look for another job.