First of all, I wish you all the strength imaginable to get through this, which I wish for you as a family together.
First, settle with yourself and the diagnosis. And maybe then is the right time to accept tips or similar. The book The Anti-Cancer Diet helped me a lot. Especially on the subject of breast cancer. I have a family history too and was looking for a way to do everything within my power to prevent its occurrence, which of course is only possible to a limited extent...
And maybe I can take away your fear that you will never get insurance again... I also fell through the entire insurance network. At some point, my employer offered a disability insurance without health questions through Generali. It is of course not the cheapest insurance with the highest payout, but at least I have disability insurance now. And in case of emergency, I will be able to live well on 1800 €. Along with the loan, we took out a residual debt insurance and an insurance that covers loan installments in case of incapacity to work. So if I get sick, I can first live off sick pay and then disability insurance. The other insurance will then cover the installments, so the house can also be maintained. And my husband is still there too.
Then you only need legal protection insurance to enforce all that (-;