Such a heartache that the sister could not appreciate her brother for taking care of their Mom. This happens often, when a child is faced with the fact that they chose not to be a part of the care of an aging parent. Children should not think that they would be not in the will when they are not involved in the care of their parents. They think parents should leave things equally to all the children. Your MIL did make the appropriate decision in her will.
I did not face such a thing, although my SIL seemed to be angry that my husband chose to have life insurance for me and had made my husband the executor of her will. MIL passed a week after my husband. MIL chose her other son after my husband. The golden daughter was not chosen to handle the estate and she just fell apart. My husband had just died and she was calling me asking me about Mom's bank accounts. We still do not speak, she is still mad that she was last choice to handle things.
I did not face such a thing, although my SIL seemed to be angry that my husband chose to have life insurance for me and had made my husband the executor of her will. MIL passed a week after my husband. MIL chose her other son after my husband. The golden daughter was not chosen to handle the estate and she just fell apart. My husband had just died and she was calling me asking me about Mom's bank accounts. We still do not speak, she is still mad that she was last choice to handle things.