When someone in your family dies you always have feelings of guilt about what could have been and what you could have done, often despite the fact that you know they were not a good family member. Jeannie 99 you are grieving for your mother as you say and, as others on here have said, for the relationship you never had with your brother.
In the last year of his life, my father was in a care home because he had somehow recovered after a spell in hospital when he was expected to pass away. He had another ten months of life, with very little quality of life though. He wouldn't leave his room and just sat in a chair all day. My brother rarely visited, although he only lived about an hour away. When the end finally came, on the day my dad died, my brother knew that dad was dying but didn't come all day but I kept saying that he was coming. When my brother arrived my dad died. I wasn't there. I found out later that he had to be almost pushed into the room to see dad. It hurts to remember these things but you just have to accept that people have different personalities and experiences. It's good to express how you feel though, and share your feelings with others.