It sounded from the OP that its not the leukemia that started this but rather a feeling thats been with him for ages. I have no advice and saying everything will be alright in the end means nothing imo. You cant just expect things to change when you do not put effort into changing it. Also **** happens, sometimes it happens all the time. Not everybody ends up having a great life.
What has helped me is doing something that gives me happiness.
What has helped me is doing something that gives me happiness.