What can I do?

I feel like my parents favor my sister. She can do whatever she wants, yell at my parents loudly, and generally create a bad atmosphere in the family. And my parents don't punish her, nor do they tell her to stop.

I asked my parents why she was doing this, and they just told me she was going through a difficult time. I respect that, but I still think one shouldn't be so disrespectful.

But if I get a little louder in a conversation or my tone isn't the best, my parents either send me to my room or my sister insults me and says that I'm always so aggressive.
My sister is 2 years younger than me so the difference isn't really that big.

You can't really have a conversation with my sister because she quickly feels attacked or loses her temper.

What should I do now?