I’m fuming. I’ve been fuming for the last few days but I’ve no idea if I’m in the right here. I’m writing this on a new account because my husband and I both post on my main account (mainly in tomb raider subreddits)

My (28F) sister (26F) hosted a little gathering in her house last week. They just finished renovating their backyard and wanted to host a BBQ. Our parents and some of her friends were there, and it was going well for the first hour until my sister mentions the dress she fell in love with for her wedding. Of course, we all ask to see the wedding dress (her husband was on the grill so he was out of earshot). She’s giggling and tells me specifically that I’ll love what she picked. Wasn’t really sure what that meant, but okay. Low and behold, she shows us a picture of the dress. My mom and I were both silent, just staring at the picture. Her friends are excited and all gushing about how beautiful the dress is. It was my wedding dress. Not even the same brand, MY dress. Not even that, it was me in the picture. She just cropped my face out. My sister then has the audacity to ask me what I think. I was honestly so shocked I couldn’t even say anything. It’s not really helping the situation that my mom keeps looking at both my sister and I, not knowing what to say. After a minute of trying to collect my thoughts, I ask my sister if we can talk alone. She’s trying to act like she doesn’t understand what I’m talking about and says “why? Is is that bad?” and her friends are now just staring at me like I’m the bad guy. My face is slowly turning red at this point. My mom finally steps in, in an attempt to not make the situation any more difficult than it has to be, and tells my sister to just “hear OP out”. Now, we’re in the living room and I’m trying so hard not to just cuss her out. She starts crying all of a sudden before I could even say anything. Honestly, I was so angry when she started crying that I don’t even remember what she said because it’s so typical of her to cry her way out of situations, but here’s what I vaguely remember her saying. She mentioned how tight money was with home renovations and what they’d spent on the wedding so far, and then had the balls to say she’d hoped I’d be happy seeing my little sister wearing my wedding dress. Obviously, I don’t want my sister wearing my wedding dress. But I asked her why she didn’t ask me about this in private rather than pulling that stunt. She dodges the question and just says she was always in love with my wedding dress, and it would really help her out if she could just borrow it for one day. At this point, I just got up, left the house and got in my car. I couldn’t talk to her without losing it because it was obvious it was either her way or nothing. I called my husband telling him to come to the car while I waited for him. Throughout the entire ride, my sister kept spamming me about how sorry she was but to please reconsider. My mother also texted me saying if it would help my sister, to maybe just let her borrow it as it’s just for one day after all. I was so angry that I showed my husband the texts and started ranting about the situation, but he just said he didn’t understand what the big deal was. I feel like I’m going insane, am I really just making a big deal out of nothing? Would I really be TA if I didn’t let my sister ‘borrow’ my dress?