"i hate my fucking mother in law"

my Mil barges in my house whenever she feels like...yesterday we did not pick up her call she called the landlord and asked him to let her in!!!! doctors have said she's mentally unstable and needs medication but still father in law does not want to accept the fact....will they put her in an asylum after she stabs me???  she keeps telling me i've stollen her son...she has till now done everything she can to break my marriage...she even nearly succeeded!!! i really dont know what to do with that bitch.  she has such a crazy look in her eyes..it scares me!!!