Is it finally time for me to cut off my grandmother?

Please bear with me; this is going to be a long one... A bit of context: Hi, my name (for the purpose of this forum) is R. I am 22 years old and am feeling particularly conflicted at the moment. I am wondering if anybody could give me some advice on this situation and I am completely lost. When I was 9 years old, my mother took her own life. There was no one major cause of this; she was a very depressed person who lived a very difficult life, she got into an abusive relationship and with everything she had already been through she just couldn't hold on any longer. When I was 12, I moved away with my Dad and Stepmum and my maternal grandmother kicked up a lot of fuss about this. She accused my Dad of cheating on my mother (untrue) and tried to say that he was taking away the only thing she had left of my mother (I am her only grandchild). After moving away, my grandmother (Joan) made little to no effort to keep in contact with me. She never calls or texts and has only been to visit me 3 times since I've lived here. One of those times was for my 16th birthday; when she later found out that I had a bank account she told me that I could have saved her the hassle of visiting and she would have just sent me money. Her way of showing 'love' is with material items. Joan has said some diabolical things to me in the past; accusing my Dad of cheating on my Mum, accusing me of slagging my Mum off, telling me at 14 that my Stepdad killed my Mum and is the reason she's dead, telling me not to get upset over my Mum's death because just makes other people upset, etc. 2 years ago, Joan and I got into a huge argument after I tried to tell her that I wish she would make more of an effort to make contact with me and that I would rather spend time with her than have her send me money. She started shouting at me, completely disregarding my feelings and telling me that I was just trying to make her feel guilty. I got angry back and told her that if she has a guilty conscience then it's due to her actions, not the conversation we were having. Joan and I now only speak when my Grandad calls me and he puts her on the phone, the only reason I speak to her is so that I don't upset him as I know he hates to be in the middle. Today should have been my mother's birthday and I received a call from Dawn (my mother's sister) crying her eyes out telling me she's had an argument with Joan. It all started because I am meant to be visiting my family at the end of this month and when Dawn told this to Joan her reaction was 'Well I don't know if we have enough space for her as we're decorating' and this upset Dawn who said 'It's your only grandchild, who you haven't seen for two years and it's likely she won't even be staying with you'. The whole interaction escalated and in the end Joan turns to Dawn and says 'You made your sister's (my mum) life miserable, it's no wonder she killed herself'. My Mum and Dawn struggled to have a close relationship as Joan always played favourites and pitted them against eachother but when my Mum was at her lowest Dawn tried to help. I know this wasn't my argument but this to me is completely unforgivable and I can't ever see myself wanting any kind of interaction with Joan ever again. My Mum was such a kind person and she would be turning in her grave knowing how my grandmother has treated us. Am I right to be cutting her off or should I give her another chance? Thank you so much if you read this far through, I appreciate any advice being given :)

Thank you for your reply, she has always been this way, definitely before my Mum died. I think she is definitely a narcissist or at the very least has narcissistic tendencies. I know I'm strong enough to deal with her but to be honest I'm at the point where having her in my life brings me no joy and quite frankly doesn't deserve to have me around, I have so much guilt over feeling this way but I'm tired of it.

I would probably just reply to her as usual and keep things very surface level. Ignoring her may escalate things or cause more drama from her because she seems to be an attention seeker by saying inappropriate things. Good on you for realizing she is just not over things and blaming others for an event where families should be brought together to grieve instead of broken apart with unkind words.