Okay. Take a deep breath. You are not crazy. Your letter shows me that it is more likely that you are terribly, terribly anxious about the tests that are coming up (and maybe about some other challenges you didn’t mention). Your creative mind has come up with a way to protect you.
Obsessing about the celebrity keeps you away from your fear. It kind of works. When you are occupied with your fantasies, you don’t have room in your mind to think about the tests that are looming ahead or anything else that is bothering you. Unfortunately, you are so good at creating the fantasies that they have taken on a life of their own and become an even bigger problem than the anxiety itself.
The way to handle this is to deal with the anxiety directly. Please see a counselor to help you learn some new ways to cope when things get rough.
In addition, it may be important for you to get some extra help from teachers or from a tutor so you can feel more prepared to deal with the exams. There is no shame in that. People learn at different rates of speed and people do learn differently. Unfortunately, schools treat us as if we are all ready for tests at the same time and can be tested in the same way. It might help if you gave yourself some practice sessions in the style (essay? multiple choice?) of the upcoming tests.
I wish you well.