Sorry to hear that. Hope you make the best of your time left.
Regarding your question, idk I'd send an email to everyone I care about. Possibly a diff one for friends and family.
Here's a jumping off point:
Subject: Well... I Guess I’ve Got Some News!
Body: Hi everyone, So, you know how life has these unexpected twists now and then? Well, I guess you could say I just ran through one of those and boy is it twisty! I didn’t exactly sign up for it, but here it is. Long story short, I’ve been diagnosed with stage 2 cancer. (As BenFranklinsDick suggested, use chatgpt to spitball ideas)
Best of luck, friend. And maybe keep in mind that just cause things end, it doesn't mean they lose their value or meaning. <3