Shane,
It is only natural to be scared. I imagine that not too many of us knew anything about cancer before we were diagnosed, and it is only natural to be frightened of the unknown, especially when the word "cancer" is involved.
One can't talk you out of depression, obviously, but I want to reassure you that there is a lot of room for hope, and no need to assume the worst. Certainly going through treatment for oral cancer is not easy, as those of us who have experienced it can tell you. But we survived it and in time things get better. My life has almost returned to normal. I have gained back my weight and I look and feel just about like my old self, and probably have a better outlook on life now than I did before I was diagnosed.
Keep the faith,and keep us posted on your progress.

Danny G.