im grounded someone talk to me

Well I'm fucking grounded for stealing a beer and being to cold hearted and bitchy to my family. I was ranting to my aunt about stuff that's been going on in my life and  got heated in the moment and started talking shit about some people in the family but instead of telling me to my face hey that's not cool plz don't say shit like that in my house she told my dad everything i said. Doesn't that make her the same as me? Ranting about what i said? how am i grounded from everything but my computer (i have it to do summer school) for a whole month for being insensitive?? But my dad is super upset with me and so is my step-mom and i just feel confused on why my aunt wanted to get me in trouble, why wouldn't she just say how she felt to me so i could understand where she's coming from