Do I deserve this punishment?

Today I logged into Facebook to find a post by my sister that said "I think its funny how Alli starves herself" first of all I eat more meals than my sister every single day and I am constantly eating. I am 5' 4" and i weigh barely 100 lbs. so of course I look skinnier than the average 15 year old. But anyway, when I asked my sister to delete it off her Facebook because I dont want people to think I actually do starve myself she told me that she would. the next thing I know she commented on her first post that said "yaaa I think alli's mad" OF COURSE I MAD SHES PUTTING FALSE INFORMATION OUT TO THE WHOLE WORLD!!!!! my mom found out and she yelled at me and not my sister... I got a lecture on how I am too sensitive and that I shouldn't care what my sister says about me and that being sensitive is stupid. Honestly I am upset because no one should talk about others that way. Then my mom grounded me from Facebook for two days sentenced me to my room and told me that she is going to deactivate my Facebook the next time this happens. every five minutes my mom calls me into the computer room to show me my Facebook and brag about how shes allowed to log into it and im not....do i deserve to be punished like this?