I think my ex and her family are really rude to not at least acknowledge my sympathy card and text to her mother about the loss of her grandmother
Why do you think she didn't contact you?
I think she was trying to keep her grandma from dying for a little bit longer.
It is hard when you lose someone and there is so much to do, so it is understandable that they didn't reply yet. You need to be more understanding before thinking other people are so heartless.
Maybe.
You shouldn't give a gift or a card and ever expect anything in return, especially when someone is grieving over a loss. You should feel satisfied enough with yourself in knowing that you gave your condolences.