It is normal to be scared. I think it is harder, sometimes, being the caregiver than the patient (having been both at times.) You feel like going to pieces, but don't want to since that is the "perogative" of the patient...and you want to be strong for him!!
Just a few suggestions. You CAN share your worries and concerns, but also your confidence that he can do this and that you will be there holding his hand all the way. I assume that you are going to his doctor's appointments with him....and maybe taking notes. It is so easy to just "glaze over" when the doctor is talking and it is great to have two minds collecting the information. Particularly after surgery, you will DEFINITELY have the clearer mind and will sort of "be in charge" for a while.
I wish you both the best of luck. You are lucky to be participating in this together and to have each other.
Sara Anne