Not sure if I told everyone

My grandfather passed away over the holiday season. It was actually Christmas Eve morning. It was brought back to me today when my cousin contacted me on facebook and asked me if I was aware of it, because no one had told her till this morning. She found out on facebook, not even a phone call. I was so upset. I had thought that everyone had been contacted and didn’t think to call her or at the very least to shoot her a message telling her to call our aunt. I feel so badly because of it. I don’t know what happened, although it was a very confusing time. All I could tell her was that I was sorry she hadn’t found out from one of us. I hope she forgives us for the lapse.