Ex-mother in law problems?

My ex-boyfriends mother is really pissing me off. Today she came to my house demanding that my daughter and I to take a DNA test to prove to her that her son is the father of my baby. She believes my daughter is to 'light' to be related to her family. (He is black and i'm white) I told her I will take the DNA test first thing in the morning. After she had her rant she pushed me on the floor and I got and pushed her back and she hit the wall and now she claims she has a head injury. Which she doesn't because I checked on her at the hospital. She is a con artist! Ever since I left her son she has been doing some pretty cruel things to me such as leaving inappropriate messages to my current boyfriend saying that I'm a cheater, slut and a tramp that's out to get a guy for his money. None of this is true and the other day she left my bff message saying she seen me with her boyfriend and etc. I want this women out of my life. My daughter doesn't really even like her because she see's me crying every time this women says or does something to me. How can I get this women to understand that I do not want to keep fighting with her or better yet be bothered with her. My Ex seems like he is scared of his mother and won't confront her about her behavior. She claims she is protecting her family. I'm afraid to confront her as well because she is known to get violent with others. Any suggestions?