paranoid schizophrenia mother in law

my wife's mother is an untreated paranoid schizophrentic in the extreme.I've been a special target of hers for my entire 12 year marriage.I've endured constant attacks from her ranging from physical to verbal.we have three young sons ages 11,9,and 5 1/2.we've lost everything except our lives and pajamas in an arson fire at 3am while renting next door to her 5 1/2 years ago.It would take a book to list everything she's been doing or trying to do to me for the last 12 years.Her third husband refuses to get her into treatment even though the sheriff has told him 5 years ago to do it before she hurts herself or someone else.He's too afraid of confrontation leaving me the constant target.My 2 questions are,could she do something like set the fire,blank out,and not remember doing it?And,are my three young sons in danger with her around given her condition and past attacks on me?I'm scared to death that they are,and am trying to get her permanently restrained from myself and sons.they now live in Kauai,but she's constantly wants over here every two months to be with them.Even they know something wrong with her.thank you for any imput