Scared to Death

I am going to be a Senior in college this year and I am scared to death. I am afraid that what I have learned in college is not going to be enough for a job. I am about to start an internship with Grow PR, which is a PR and Marketing Firm in Plano, Texas and I am so scared. I don't want to mess it up, I am really unsure about my abilities to do a good job. I know that as a PR student, we should be good at writing and I am not. I like working hands on and writing is my flaw and that scares me, because I am going into a job field were writing is a must. I don't want to do bad, and I just don't know if I am going to cut it at my internship. I know what I want to do with my life after college and where I want to work, but right now I don't feel as though I have learned enough. If I was thrown into a PR job right now, I would be lost. I know it takes time and experience to be good at anything, but being put into something that could be life changing scares me. What if the company wants to hire me and I still haven't learned enough and make mistakes. Being a failure has always scared me, and I have yet to have a job that I didn't do well at, but this is all new to me. I know I shouldn't worry, and that with time things will work out, but right now I am scared. I don't want to let anyone down, especially myself, because I choose to do PR and I just hope I didn't make a mistake.