Parent doesn't know how to cope with her overwhelm, guilts us about not being able to fix it

For context, my sister and I are both in our 20s and both disabled. We truly have no ability to move out. I'm at my wits end with navigating my mom's outbursts when she's overwhelmed. There's WAY too much to sum up in one reddit post so I'll try to be organized.

We had a really traumatic childhood because of our dad and my mom spent most of it dissociated. I was baby sitting my sister by 7 while she gardened for hours, cooking on the stove by 8 for my sister, I actually had a really bad burn from it around then, and by 15 I was running the domestic part of the house in addition to being in debilitating pain, going to school, managing my dad (who was an alcholic, a diagnosed narssasist, and generally a living nightmare), being free physical labor for every home improvement project, and filling whatever other gap I had to at any given moment.

I'm at a state where I often can't do anything the whole day if I want to have the energy to cook dinner. She hates to cook. ​If she cooks, I'm often her Google. I have to verbally walk her through anything medium complicated even though she is a really good cook. I try to tell her, like today, that if I'm going to be cooking, I have to rest today. ​I woke up with terrible motor tics and pain and fatigue and I'm also still grieving my cat of 18 years, and I had a concussion a month ago. It's just...really hard right now.

I told her I needed to rest today, first thing in the morning. An hour is later she's freaking out about organizing the garage, asking if she can move my things in the spare room to reclaim a shelf she didn't have space to move yet anyway, huffing and puffing and in my sisters words, dripping with frustration. She gets petty. She gets abelist. She never remembers a single comment she makes and reverts to all the things she needs to do if confronted. She also has woefully unmanaged adhd and refuses to ever pause to breathe, reset, go outside. My dad caused a productivity anxiety in her but she has no ability to see when she's using me as her punching bag when I'm not able to jump when she says jump on projects. And sometimes, she won't stop, will injure herself for weeks, refuse to so much as elevate/ice/take pain meds, and then I'm in agony trying to take on everything. Last time lasted a month and she was snappy the whole time ontop of it, yet refused to ask for help and then took it out on us when she needed it.

I really try to coax her into taking moments to ground but it's useless.When my mom wants to do something, like house repairs, it's like the world is ending. If I can help we work well together mostly, but she also doesn't listen. Like at all. It's one ear out the other about many things and she'll swear you never said a thing. It's like herding cats. And I have a bad short term memory, I try to compensate, but she just...doesn't. She also has a phone addiction which doesn't help but she lost the progress she made in therapy when she lost access to it. And she did convince her therapist she was managing very well, so...​

There is alot she does for us and I don't want to loose the gratitude for that beneath this. But she can not create boundaries within herself to know when she's anxious and deal with it. She will push and push and guilt and try to wiggle around any boundary you set about your limitations. And if you say she's being unfair, she starts talking about her garage organizing plans with urgency to overtake you and soaks in nothing.

She's lonely, and she ofloads it to me. She doesn't look up to see if I'm busy before divulging about horrible things in the world that she knows I'm not equiped to hear about while I'm trying to rest. She refuses to talk to her friends and only recently started talking to her sister more. She is on something for depression but my hands are still tied because it takes forever to get her to make a doctors appointment. ​It takes 2-3 years, on average, to even convince her to change something. So maybe this will get better someday but it's bad for now.

I am trying to just...force independence for myself in what ways I can. It took years to make her accept payment for utilities, after her not letting me shower for days at a time because she would only let showers happen at certain times with specific circumstances. That's better now. Right now I'm trying to take over the grocery planning so that she stops getting so weird about it. If I wasnt here she'd be cooking nothing but veggie burgers and nachos and as is its like going to war justifying buying fruit most the time. But I don't know what to do here. I'm so exhausted.