How would you feel?

My fiance and I have been engaged for a year and selected our date almost 6 months ago. My cousin, who is more recently engaged, reached out to my parents to see when our date was to make sure that it wouldn't conflict with ours. Well, come to find out today she booked hers 1 WEEK after ours. I'm not taking this well at all. Why even ask when ours is if you had planned on doing this? I feel like it's just crappy etiquette on her part. She could have picked any other time but no, it has to be this close to ours. I was really happy for her when she got engaged, she had waited a long time for this, and I'm sure that she didn't intend to hurt me, but still, I can't help but feel hurt and angry that she did this. Am I overreacting or would you be upset too?