This is exactly what you have to do, and exactly what will happen, when/if you go NC.
All of this.
I went NC with my (likely NPD) father, after a last straw event when my first child was 3, and this is how it played out.
I have a few other things to add.
First, the guilt and grief of NC a parent can be enormous at first. For me, it felt like I was breaking a sacred covenant, it felt viscerally, primally wrong, like an abomination. It felt like I was the one who was at fault. Because I felt responsible for him (parentified), I also worried for him, who was going to look after him? I ruminated endlessly. I walked for hours with the dog at night, talking to myself, trying to manage and process the emotional pain. And the emotional pain literally caused physical pain, stomach pain, to the point I got tests, fearing I had cancer. All clear, it was "just" stress.
Second, the pain dwindles. After a year, I had stopped thinking about my father. After 5 years, I realised that I hadn't thought of him for years. After 10 years, I came across some emails I had written to myself in that first grieving year. I read them silently, shaken. And then I mentally embraced that struggling and sorrowful younger me. I thanked her - and still thank her - for her courage and resoluteness. Due to her, my and my children's and my H's lives are free of the emotional violence, chaos, and destruction that is my father.
Third, I think therapy would have helped a lot. Maybe it would have sped up the process a bit, or made it less painful.
Fourth, it's best to not announce NC or discuss anything further with your parents and any likely flying monkeys. All this does is pointlessly trigger the NC person. People like your mother and my father have an echoing, viciously grasping need to be centralised, their existence authenticated. There is no point in activating their fear and angry defences with something they can focus their energy on.
Fifth, if NC sounds too drastic, you can try gray rock. Pull back, steadily reduce contact, visit them for an hour once every 3, or 6, or 12 months (whatever you can tolerate), never let them on your territory again, make excuses, lie through your teeth if necessary, ruthlessly change the subject. Be bland, boring, busy. "No, everything is fine, just busy." NEVER get sucked into (i) explaining yourself again, (ii) thinking that if you find the magical words *this time they'll finally understand, and (iii) - this is hard - allowing their genuine emotional pain (because they can't feed on you anymore) to sway you from your course.
In my case, straight out NC was the only possible avenue. It was bloody excruciating. But ultimately, it was completely worth it.
Today, I view my father - who is still alive at 90 - with distant compassion. I know why he became like he was. I wish him well. But I don't want him in my life. We can't choose our parents. But we CAN choose who is in our kids' lives, and I chose to exclude from my kids' lives my ruinous mean father. I broke the chain, and I'm glad I did.