My sister asked if she could borrow my wedding dress for a photoshoot. That dress is really sentimental to me, and I am not comfortable letting it be used.I explained to my sister that it’s so important to me and I’d like to keep it safe. My sister reacted getting really upset. I don't know if I dealt with this correctly, so I’m wondering if I crossed a line. It is my personal item with a lot of emotional value, and I shouldn’t have to share it if I don’t want to. So AITA for saying no to my sibling?