mothers behavior

My mother has been showing signs of mental illnesses for a very long time, specifically kleptomania, as well as, the inate need to cause problems for everyone in our family through lies and deceit. I mean purposely lying to hurt people. An example might be that she will call a family member to tell them that thier spouse is cheating on them even if it isnt true. Also telling lies between family members like she said you were lazy or stupid, stuff like that. We (brothers and sisters) have been dealing with issues like these for years. We all have this inate need to just let her get away with it. We feel if we approach her she will just lie and would never admit it. People have confronted her to no avail. It leaves us feeling guilty for the things that she does and our interfamily relation have suffered because of this. We are not close and trust is an issue between all of us, we also have a hard time dealing with any feelings. She is a good mother other than that but she has this mean side to her its as if she isnt happy unless she is making someones life miserable by creating contraversy. I can no longer deal with this personally and I want the behavior to stop, is there any thing i can do to change this. She is 85 now and i know its probably too late but if this doesnt change then i dont want to be around her anymore, its hurts too much to have to deal with this but im afraid she will die and i will feel bad if i dont see her often.