Hi so sorry to hear this my grandad has been recently been diagnosed with cancer too, he is also going through chemotherapy they cannot get rid of it but it prolongs his life a little more. It really depends with chemotherapy the doctors may say a date but people do surpass it. I feel like the best thing you can do at this time is to maybe talk to someone professional about how long he has but don’t be worrying about him passing constantly try to enjoy the most of the time you have with him even though it is really difficult knowing they will pass away you have to make the most of the time you have with them as much as you can. I hope that you feel better soon through this hard time if you would like to chat feel free to give me a message as I am in a similar situation.

Best wishes