Bean-I'm the Moderator from the Main Board, and I just wanted to welcome you. I think you will find the boards a great help to you. I know that it must be hard on you to see the changes in your mom. Grief does that too you, and the loss of a child is devastating. I know that you must feel a lot of pressure and expectations, being the only child now.
I am sure that others who have lost Siblings will be along soon, and perhaps some of the moms who have lost children can also help with some advice, about how to deal with your mom in a loving and compassionate way. But I understand what you mean about the anger, and it just destroys everyone else as well. But she is grieving for her child, and doesn't know anything to make it better. And it is understandable. Just know that when she is angry, it is not your fault, or even about you. You sound like a wonderful person, and the holidays are so difficult when a loved one is missing. I am sure that some of the others can add to this.
I am so sorry for your loss, and sorry for the way it has changed the happiness of your family. Please drop by any time. Lonnie