I did it last year for four months with a bi-polar, senile, just plain crazy mother-in-law. It was horrible and I lost my heart and mind for several months.
My sympathies, sometimes though there is no other solution than for you to just march on. I cannot imagine having a running battle with an insane person in my own house. OTOH, my M I L lived with us for 3 years, before finally going to the nursing home. It drove my wife nuts for some reason, she was very sweet and non demanding. My wife thought that she was very demanding, but she never asked for anything except time. She wanted someone to watch "Wheel" or "Jeopardy", someone to visit with is all. She slept in her own room, the only thing she needed was help in and out of the bath.