What Causes Personality Disorder?

I MOVED BACK IN WITH MOTHER TO TAKE CARE OF HER. I HAVE COME TO THE CONCLUSION THAT SHE IS A NARRSASIT. SHE HAS BEEN VERY VERBALLY ABUSIVE, PHYSICALLY, MENTAL, PLAYS GAMES BETWEEN HER CHILDREN, MANIPULATES, LIES LIES LIES. I HATE TO LEAVE HER WHEN SHE NEEDS SOMEONE BUT I FEEL MY OWN MENTAL HEALTH IS AT STAKE, AS WELL AS MY 28 YEAR MARRIAGE . WE ARE SECRETLY LOOKING FOR SOMEWHERE TO MOVE, SHE WILL GO CRAZY WHEN SHE FINDS OUT. ANY SUGGESTIONS.