Really struggling with my mom's family this year

I've posted about this here before, no idea which account since I lost my alt after getting a new phone.

I came out to my mom, who I was already on shaky ground with for years before due to her marrying an emotionally (and probably physically) abusive man while I was young enough to still be court ordered to visit her. She didn't take it well, and then like a week after I told her, my grandmother was suddenly diagnosed with cancer and died just a little over a month after that. My mom made me vow not to tell either of my grandparents, saying that it could kill them if I did. So I didn't, and then my grandmother died on my birthday, and that's probably my biggest regret I've ever had. That was last year, and this year a couple months ago, my grandfather found out about me after my dad slipped up and called me my chosen name in front of him. His reaction wasn't great, but it wasn't terrible. I think that when he dies, my mom will blame it on me. She already treated me differently, but after he found out, she stopped regarding me with any kind of emotion other than the occasional crying outburst. I feel more disconnected from her now than I ever have.

All of that is to say, I'm really fucking struggling this year for some reason. Everything's going great in my day to day life—I just moved, I'm getting a promotion, probably getting a second job. Things are fine. And I already got through the whole "my mom isn't the person she used to be/should have been" thing with my therapist a long time ago. When I finally had the revelation that I couldn't change that, after I grieved for a little, I felt better than I ever had. Now, it feels like that's coming back and hitting twice as hard. My mother is such an enigma that talking about her has stunned multiple therapists into complete silence, including her old couples therapist and my current one, which is comforting in its own right because it means I'm not crazy thinking that she's so messed up. But I also really wish that she was solvable. It's like she's the world's most complicated mystery. She has SA related trauma from her childhood, too, and I know that she never got help for it. She doesn't know that I know. I feel like when I turned the age that she was when it happened, something inside her relating to me kind of just broke. And I don't know if I broke it or if it was just inevitable anyway. She is a fundamentally completely different person now than she was when I was little. She was a huge role model for me as a child for being different and holding onto individuality. It's like she became the opposite of everything she always preached about being. It's really hard to put into words how it feels not to recognize my own mother anymore.

Honestly, if anyone knows of any subreddits more specifically suited to this kind of issue or if anyone who reads this has a similar experience, it would be great to hear from more people who can relate. I'm fine with well wishes and all that too but it's really helpful to actually talk to people who have the same kind of relationship with a parent. I'll also take book recommendations about the topic. Honestly, anything.