Even though my logic says it will be handled and might even be cured ,I just can't stop feeling kinda doomed and sad at times.
Pretty rotten disease , isn't it 
Some wise person once told me when i started out looking for support during my sister's fight with breast cancer..."We all die." It was almost a slap in the face, it made so much sense. Simple common sense. It's just that we don't think about it, keep it blocked from our consciousness. A word like 'cancer' stirs up fear, to be sure. Mostly fear of suffering, because of the way we've been programmed to think and feel about cancer and death.
But there is the gift of time that comes with cancer. I mean..it beats getting hit by a bus, there is time to take stock of things. Sometimes it brings out the best in us, too, as well as the worst, of course.
Cancer survivors are vulnerable, and every ache and pain will be scary, forever, I guess. I"m 8 yrs NED (no evidence of disease) and have had a number of scares. With time, I got less panicky when something hurts. It got easier with each scare.
I lived from follow-up to follow up the first few years post-dx, made a plan for a vacation and just looked forward to that, as if I wouldn't make the next six months. It was stupid. I'm beginning to realize how much time I wasted preparing to die happily instead of live happily. Doh!
As a newly diagnosed person with treatments ahead, you're in the toughest position, but keep in mind that treatments are temporary, you will heal. You might find that 'survival mode' kicks in to give you courage you never knew you had.
xoxo