In circumstances like this some individuals may resort to pushing others away. He just needs to think "Is this what my mum would want me to do?". Give him space and time and be there for him when he needs you to be. It is understandable but unacceptable to take his feelings out on other people. If it is contained in one area, is it stage 1 cancer? If so, she could have a long time left yet. Have you saw the oncologist yet? He explains what the treatment plan is and how long she may potentially have left if treatment does not work and will answer all your questions. Maybe ask him if he wants to join a support group, talk to macmillan nurse professionals over the phone who help with anyone coping with cancer or talk etc. At a time like this you have to be the strong one and help him as much as possible. Try to spend time with him and his mother if possible, because naturally he would want to spend a lot of time with his mum. Let me know if you have any other questions.