How would you handle a disrespectful family member?

My grandmother likes to start drama within our family. My wedding is coming up in a month and it seems like this is her new focus. Instead of letting things run smoothly, my grandma has been causing problems as often as possible. She nearly ruined my shower on Sunday by sending me a very nasty and disrespectful email the night before. She was upset that the RSVP card for my cousin and his girlfriend said “Mr.Smith plus guest” instead of writing out his girlfriend’s name. Keep in my mind, everyone who wasn’t married had the exact same wording. But the family still flipped out.

So here is my dilema…My grandma has been at her little games for years and I’ve always let her get away with being rude, disrespectful, and evil. But enough is enough. This time around I wrote an email back to her explaining that my cousin and his s/o were not discriminated against in any way, and that if they continued to start silly drama that they can all skip my wedding. I want no negetivity on the big day. I also went on to defend myself and let her know how badly she hurt my feelings by sending such an awful email. This is not the first nasty email from her. It’s been a few days and she still hasn’t responded. My mother spoke with her yesterday and it turns out she’s upset about it. My grandma pulled the “I’m her grandmother and she should respect her elders” card. My mother is 110% on my side and understands how rude my grandma is and always has been.

So, here is my theory; in order to get respect, you must also give respect. Yes, she’s my grandma. But she has never been respectful of me or my family and it’s time someone stood up to her and let her know how wrong she is. Am I right? Or did I handle this inappropriately? Have you been in a similar situation? How did you handle it, and how did things turn out between the family?