Showing future MIL my dress

So I bought my wedding dress yesterday with my mom and my MOH there. I really love my dress and think it is super unique so I really want to keep it a secret from everyone until the day of (our wedding isn’t for another year.) I know that my future MIL will be asking me to see it but part of me really doesn’t want to show her because she can’t keep a secret. Obviously she wouldn’t have a picture of it to show anyone but I’m worried if I showed her a picture she would go and start telling all her family what it looks like and it would get back to my fiance. I don’t want her to be upset or feel like she isn’t included but I also really want it to be a big surprise and not have the word get out on the details of it when there is still a year to go. Any advice on what I should or say if she asks to see it?

My mom and MOH told me to just tell her that I don’t have any pictures of it but obviously I can only use that excuse for so long. I see her pretty often and we still have a year to go so I feel like that excuse would only work for so long. She is also very controlling and we have already had to talk to her about backing off and explaining this isn’t her wedding, its ours so I’m worried about causing more drama with her.