I have discovered that the thing to strive for is acceptance: that doesn't mean giving up and assuming the worst, but accepting that uncertainty is now part of your life.

No one can tell you for sure what is going to happen; maybe it will be better than you expect, or not. Until something like a cancer diagnosis happens, many of us live with the illusion that we can control our lives with some degree of certainty. Discarding that illusion is hard, but it can also make us better people.

I know this won't help a lot now because you're still in the initial shock of your diagnosis, but I hope in time you find way to a place of acceptance as well. I'm still working on it, but the days when I find it are my happiest.