Must I fast Ramadan which I broke due to illness and for which I fed [the poor], and do I have to feed [the poor] again if I perform the fast?

If your deviation from making up the fast to feeding the poor was based on the report of a trustworthy doctor that your illness is incurable and your incapacitation is continuous, then you are not required to make up the fast in the future if you become able to fast. However, if the deviation from making up the fast to feeding the poor was for a reason other than a continuous, incurable illness, then feeding the poor does not absolve you of your duty, and you must make up the fast whenever you are able, as breast cancer is among the diseases that are hoped to be cured if it has not spread.