baby shower drama

Casey
So my parents and sister who is a few years older than me shower up early to help set everything up. My sister laid on my couch insisting she didn't feel well which in turn upset my mother to no end and she was annoyed that her and I were the ones making a hundred trips in and out of the house and up and down stairs. I put my husky in my bedroom wth air conditioner running and tv so that she wouldn't get overly excited or stressed with the commotion. I checked on her and she peed on my bed a small spot. She was mad at me for cooping her up. I went downstairs and put my blankets in the washer and complained to my husband which my sister overheard. An hour later guests were here and everyone enjoying themselves and I overhear my sister telling about 12 of my friends and family how my dog "pissed all over" my bed. Then a family friend gasps and says oh your doggie peed on your bed omg... 
I became so upset and angry I wanted to cry!!!! My response to the family friend was don't get me started and I kept my cool and walked away to be alone for a moment and then complain to my husband. Why would my sister tell people that? What is wrong w her? Am I wrong for letting this make me really mad? Later on when we were alone I expressed to her that it upset me she said that. She said sorry but that was it like she doesn't even get why that would upset me?