My husband has a rare incurable cancer, which will end his life if nothing else does first. The NHS feels like it moves slowly whilst they are deliberating and investigating, but in our experience once a course of treatment is decided on they start moving more quickly.
My husband is also a worrier, but the worst has now happened so he's actually a lot better on this front as a result. We're coping by having conversations about how he wants to live, what he wants to spend his time doing, and anything else that's important to him. We have time alone together everyday and no topic is off limits. Sometimes he doesn't want to talk, we just go for a walk in the fresh air, maybe go to a nice place, or grab a coffee, and just be together.
I'm living in the moment and not thinking too far ahead, and that lets me hold it together. I also feel like I'm not wasting the time I have left with him if I stay in the moment - I'm not going down the 'what if' rabbit hole. It is an awful, awful situation, life will not turn out how we planned, there's no getting away from that, so I'm just trying to look after myself and be as positive as i can so I can make this a bit easier on him. If he doesn't have to worry about me then that's one less problem for him.
If I feel like a good cry, I normally go for a long walk on my own, the countryside distracts me and the cold air makes my face less red. I've found that crying is exhausting and I feel terrible as a result, never better, so I've been crying less and less as time goes on.
I think that it's not necessarily helpful for people to say 'my cousin/dad/friend had this and they are fine' as everyones cancer will be different. But I'm saying it anyway as you might find it reassuring. my uncle had stomach cancer and had his stomach and most of his esophagus removed about 5 years ago. He's fine. not as fit and healthy as he used to be, and definitely a lot thinner, but alive and living a full and happy life.
Good luck.