My mother has Alzheimer and is jealous of my children?

My mother is 82 yrs old and she lies a lot and steal things from other bed rooms.she is also having some rival with my 12 year old son.she thinks i am her mother and is fussing with my son like she is jealous.i dont know what to make of rhe situation.i need some help.i dont want to have to put her in an assited living bit my kids are very uncomfortable with her behaviour.please give me some advice.