Can I take my sister to court for slander?

She is accusing myself and my mother of emotional abuse for when she was a little kid. The thing is, is that she wasn't abused. Somehow, her memory has tweaked everything and now all the times that she didn't get what she wanted, or felt badly about herself have turned into abuse. She and I are the same age and I never felt like we were abused. She continually says my mom and I emotionally abused her because everything "revolved around" me. It didn't. My mom and dad were like any other set of parents. Her husband has also threatened us, claiming he'll get a restraining order, which is stupid because they live in Utah and we all live in California. Can we take her to court for this? All of her accusations are false.