My beloved cats died after two months of adopting them out!

My beloved female cat, Sierra, was recently put up for adoption as was her mate, my male cat, Mylo.  I have had these two beautiful gifts from God since their births, one year apart of each other.  Sierra and Mylo were stressed out so badly, I was told living without me to care and love them so very much that the stress developed life threatening illness in both my cats.  Mylo had two seizures and died.  Sierra was diagnosed with liver cancer and died not long after.  I have been devastated ever since, because, I was not able to quickly come up with money to care for them properly at the vet's office.

Could you please inform me on information to cat's developing liver cancer and seizures and what I could have done differently?  I am most grateful.

  Thanks,
Lorraine Tauson