Concentrate on your breathing. Continue hearing him and seeing him, but don't focus all of your thoughts on him. Relaxation starts with breath control. You don't have to be worried. You don't have to be self assured. All you have to do is BE.
Don't worry about what you're GOING to do. Just be open, and do what you must. Regardless of how angry/crazy
he might be, he's a person. Try not to hurt him!