Can you please help? My family is going through some major problems!!!?

Okay, here's the story...In the summer my mom and my oldest sister had an argument, and from this argument many things have been happening. When they had this argument, my sister said some things she never said to my mom in her life. She said,"I've been hating you for a very long time." And like my mom, I mean she's a mom, she was shocked and petrified. But the thing is, this was outside, and everyone was around. My sister kept yelling that she was going to call DCFS on my mom, because my mom "supposedly" abuses my brother who has Cerebral Palsy. I live with my mom, brother and grandma, and my mom does nothing of the such. But this is the thing, my sister has been going around to different people (strangers and extended family) spreading rumors like my mom had with my cousin, and that that same cousin is my brother's father. My sister claimed she was going to call a meeting, because she came up with some term paper, and that she was going to represent my brother in court???? HELP!