Getting Rid of the Family Name

My boyfriend of five years and I got engaged in May. I was so ecstatic and started planning pretty much right away. I posted a picture of my fiancé and I on our first one year anniversary reminiscing and stating how excited I am to officially be his wife on the same date next year (August 28th 2019). Long before we got engaged we joked about how we would get married on our anniversary to seem cheesy and not have to remember another date. This was a cute way to celebrate us and my grandmother June... Responded like this.. She was mad at me and even sent me an email after this being mad at me for my wedding date. I had no idea about my cousins, she has not sent out save the dates (my whole family knew her date but me). My date means something and hers doesn't.. They are not on the same week or same day (she's the 24th). I just can't believe it. I have had family members on my side tell me they aren't going to mine because of the date I picked...