My ex's mother. Do I need to be in contact?

Hi IMs

I left my abusive partner and father of my two year old 9 months ago. He was physically, verbally and mentally abusive toward me. He also has a drinking problem. I have an intervention order protecting myself and my child.
We have a two year old. I agreed to mediation and he is only allowed supervised visits at a family services centre with our child.
My problem is that his mother still wants to see the child, regularly. I know she is the grandmother and normally this would be fine. However she has enabled her sons behaviour his whole life. He is a spoilt brat who has never been properly disciplined and as a result grew up to be abusive and violent and used to getting what he wants. Even when living under her roof she would take his verbal abuse and violent behaviour and do nothing! She has helped him financially many times and always makes excuses for his bad behaviour and has even blamed others when he has been the instigator.
His father was abusive (her ex) and she left him and raised my ex on her own, he is an only child. I don't understand why she cannot see what a horrible man he is and stop pandering to him. Also given the fact that she was abused herself, you would think she would understand what I'm going through.
But no, she supports her son. All while still wanting to visit me and my child and wanting a relationship with her grandchild and expecting me to be nice to her and welcoming. I'm finding it increasingly difficult to tolerate her when visiting me in my home she still makes excuses for her awful son and minimises his behaviour and abuse of me.
Also, I should mention that he hates his mother and has not spoken to her for months yet she still remains hopeful he will call her! Any little crumbs he throws her she is there ready. It's pathetic.
What should I do? What rights do grandparents have? Seeing her makes me uncomfortable and I know it's important for the child/grandparent relationship but at the moment it is causing me a lot of stress. I can't trust her.