Is My Stepmother Mental?

My stepmother started talking to my sister. She never spoke to her before this summer.
She claimed she loved me and wanted the best for me..This is what she told my sister at FIRST. ( but when i was told this i was shocked) because the woman was always emotionally abusive and hated me despite me doing anything wrong and i kept away from them for like the past 10 years or more.
Then after she says this she makes up this story and tells my sister that everytime i saw her, even as a child, i greeted her with “hi wh*re” whenever i saw her. She claims I called her a wh*re and would repeat this numerous times to my sister doing impressions of me supposedly doing this to her.
She also claims I hit her, that’s the reason she wouldn’t allow me in her home. * which is a lie* as well.
Why would she say all this and make these things up? My father just sat there some of the time while she said this and didnt say anything!