Should I body shame a my wife to get the money back that she spent?
Why? Are you trying to get the money back because she didn't spend it on you?
Yes, she wasted it on a dress that is too small for her.
You may not like the fact that your wife bought herself a dress, but embarrassing her over money will destroy your relationship. Let the money go and be happy for your wife that she got something that she wanted.
Ok fine, I'll just stay home and get a good meal from my loving wife.
That might be better than trying to break up your marriage just for money spent on a dress. Your marriage and family should mean more than that.