Impaired family functioning

My brother suffered a cardiac arrest on March 20, 2011. On March 25th he suffered another 10...yes ten arrests. He was in the cardiac ICU at the time, and thankfully the staff responded quickly to his needs. He had to shocked 150 times during this crisis. After this happened an Impella device was implanted to help with his heart recover. TO make a long story short, and also to keep from crying and having a flashback, my brother is at home and doing physically wonderful! My question to anyone what can my family do to help my sister in law cope with the stress at home? My sister in law has two children. My nephew is 3 and he has Down Syndrome, and my neice is 17 months old. She is constantly urging my brother to help with everything and demanding things be done. My brother tries his hardest and he seems that it is not enough. She did tell me he does get aggressive and impatient with her. He begins to yell at her and degrade her. My family feels that this can all be avoided if she approached every situation diffrently and smoothly. When we are around hime, or when he spends time with us alone, he is happy, patient, and cheerful. We make sure he gets some sleep...since he says she doesn't let him sleep at home. We all know that when he does get enough sleep he is calmer and able to function mentally at 100%. He is still not back at work and currently trying to work on his short term memory which we feel he is getting better every month at least 10%. Can anyone help me please?? Any suggestions on coping for my sister in law? She refuses to get help for herself...What do we do??