I'm really sorry to hear your are feeling so down about this.
Giving presentations and doing interviews are not nearly as scary as you think, it's just that we can get all worked up about things like getting embarrassed, stressed and saying the wrong thing (which you can't actually do in fact!
What is it that is worrying you?
Remember, the interviewers are just as nervous as the interviewees.
Just be yourself, show your personality and enthusiasm. Have a laugh, see it as a bit of fun and a learning experience. Forget about the outcome.
One thing, if you don't try you'll never overcome this irrational fear of interviews and presentations.
So, research your topic and get in there! Apply and do the interview - it will be fun to see what you know!
Best of luck and tell us how you get on.