My school had a great counseling center. It helped me to see my negative bias and learn to fight it.
As for the unpardonable sin, I have wondered what that is. May I state my theory? I think it is the refusal to accept Jesus as your saviour. The sin was mentioned when the people accused Jesus of removing demons through the power of Satan. I have wondered about it because I once thought that I had done the sin. I somehow managed to stop thinking that way.
As for your grades, I doubt they will kick you at for old grades. However, I am glad that you are going to talk to the school counselor. He/she may be able to help you figure out how to acheive graduation despite your ilness. As for talking to others, I agree with the previous posting, it is hard to share thoughts with some people. Some people just tell you that you shouldn't think that way.
I would suggest a different counselor. I didn't read any comment similar to schizophrenia. Of course, I am not a counselor. But, I have a classmate who received some kind of personality disorder dx that wasn't true. A Christian counselor set her straight on that. Perhaps you can find a counselor who can help you straigten out this situation if it isn't true.