I'm sorry that you're feeling so stressed. Cancer is always something that will often make people feel that way and it's perfectly valid for you to be worried.
For me, talking to a friend comes easily as I have a very close friend I'm used to telling my troubles to, but I'm sure it's not that easy for you. If you have someone like that to talk to, I think you should really go ahead, I usually find that it clears my head up a whole lot. If you don't have someone to talk to you can try some coping mechanisms. I normally chew a lot of gum, but I've heard excising can help a lot with most people as well as help them sleep.
If you need really need to discuss, don't forget there are listeners online you can text/talk to! https://www.7cups.com/ Don't feel ashamed of talking to them! (I've never used this before, but you might want to check it out.