I think the question to ask yourself is what is your goal in confronting her? Is it to give her the chance to be the mother you always wanted her to be, to show up and fix her behaviour and apologise? Is it remorse and understanding and a changed relationship? Or is it that you just want to honour your values and be honest so you can know that at least you didn't leave her hanging and made her aware of why things were going to change? Think about this. Hard.
I tried to talk to my mother. I did a load of therapy and realised, she's never really helped me or taken an interest in me. My mum is a good person and she can get distracted. And to be fair, ive been abroad and im pretty independent. l'll tell her and it'll make the relationship better. Simple! And instead I got talked down to, gaslit, lectured, dismissed, invalidated. On a loop. That happened for a few years, then I got engaged, then married, then infertility and she played the same non-existant role in my life and my eyes were very much open. I told her she never was a mother to me. I stopped answering the phone. I stopped visiting. We had an almighty phone call where she...half apologised about things that happened 20+ years ago, denied things that were happening today, blamed as much as she could on me, made it all about her and guilted me about getting old, only a few years left blah blah.
It was all honesty very re-traumatising. My life was hard and I kept just looking for a mother. And instead I got traumatised again. I walked around not knowing what was real, wondering if I was going mad, feeling so bad about myself. I'm still susceptible to feeling that way if I think about it too much. But I learned the hard way that the woman is not for changing, my feelings and wellbeing will never matter to her, my life and experiences are not as important to her as her own, and she needs me in an invisible role to be able to function as a mother. She's not about to acknowledge she did a thing wrong, and she will hold me accountable for saying a single thing that she doesn't like via scapegoating and discarding.
Anyway, this is longer than I intended. But I'd implore you to really think about what your impulse to have a conversation with your mother is all about, and what impact her emotional abuse is going to have on you. You're allowed to just go off the grid. You're allowed to not answer her calls, or set a boundary and ignore her violations. You don't owe her anything. Healing requires your needs to matter more.