I can understand why worrying about the exam would bring back unpleasant thoughts of the incident, and unfortunately I don't think there's a lot you can do about.
In the UK I'd say you should speak to a counsellor. I don't know if they exist at your college.
But I am able to cover it, I am scared because I work hard for exam, I do not want to spoil my paper, anything can I do so that I again create focus on my exam.
Sir John Rennie is giving excellent advice. My advice would be that surviving such a close call with death at this point is a sign from God that you should try your best to concentrate on this exam. Count your blessings my friend.