I am so sorry to hear this. I know what a shock it is. Maybe you will get some news today that will soften the blow.
It is natural to grieve at this time, but try to remember that there is hope. 50 is young for this disease, and often younger people have slower progression. I have read so many stories of people with children like you, who were given only a few years to live, but have survived to see their children graduate, get married, have kids and more. You have so much to live for. They can't cure this disease, but modern technology can keep you alive and communicating. You can be there for your children. It is all too much to take in now, but in time you will be able to find a way forward.