When Old People Are Mean

I have a mean grandma. Yep. That is right. Grandma. What prompted me to be honest about this was something she said tonight. She has done worse in the past. This however was half mean and half funny which is a whole heck of a lot better than the crap she pulled at Thanksgiving. 

My grandmother isn't a sweet little woman. She is mean, harsh, narcissistic, and hateful. I'll leave the adjectives there because I don't want to be brutally honest (out of some respect).  

She has never been a nice grandma. She slapped me across the face as a child because I wasn't fast enough bringing her a washcloth when my baby sister puked on her. I never realized grandmas were normally sweet until I met my best friends grandma who was always an absolute doll to me. 

Tonight my grandma called my parent's house while we were there having supper. My mom quickly got off the phone with her by saying that we were eating. Two minutes later she called back. No one answered (she has a habit of doing this). She called again so I answered. She asked what I was doing and I responded with eating supper. She said and I quote "you are like me and don't need to eat supper". Yep. That is my grandma. 

On Thanksgiving my mom made 2 coconut cream pies because they are a favorite of mostly everyone-my grandma especially. My husband knowing this joked to my grandmother that he was going to take 1 whole pie home. They joked back and forth about it. No biggie. Right? Wrong! By the end of the day there was one piece left and my mom said for us to take it. We didn't even think about it because it is merely a piece of pie. We left the one piece in the original throwaway pie pan. Well my grandma really thought we took a whole pie home. This really did happen and yes I know how silly it all sounds. So to make matters worse my grandma called EVERYONE we know to tell them about stealing the pie and then she added extras in that were complete lies. I ignored it for awhile until her lies got bigger. The people at our Thanksgiving gathering that day knew what really happened but who wants to stand up to an elderly lady who can throw down some tears when she really wants to??? 
I eventually just pretended she didn't exist. She admitted she may have took things too far (but not to all the random people she told) and I started to have minimal contact with her again. I have seen her twice since Thanksgiving and tonight she basically calls me fat. It really makes it hard to be respectful to mean grandma even if she is elderly. 

What would you do about a mean grandma?