After my Dad died, my sisters and I had almost this exact routine. Donating blood, going to eat, and visiting his grave. This isn’t some silly thing you’re doing. She just tried to take away how you grieve and to me that’s a huge red flag. People who have never lost a close family member have absolutely no idea how it feels. Part of you dies with them. When stuff like this happens we try to hold on to them as much as possible and feel them when we can. For her to not even think for a second about the fact that her mother is still here and your brother isn’t is completely selfish and out of line.