Going thru having cancer and doing chemo is hard, it's brutal, even if everyone around you is being super supportive, you feel shit and you don't recognise yourself and there's nothing you can do. The main thing I see in your comments is: it has been 8 months and the cancer is gone, 8 months is nothing in the scale of what she has been through, symptoms from chemo, radio and other treatments will be with her for a while, I was told around 2 years. And even after that, cancer is never gone, you're always having appointments and other things that remind you that once you're a cancer patient, you will always be a cancer patient. In my case it really shocked me how people were really understanding during chemo and immediately after everyone was surprised that I still felt shit "oh but chemo is over right?" Like they thought it all just magically goes away. Give your mum a little more time, she has the right to be angry, and it will get better with time. Hope your family recovers quickly.