How to reply to mother hurtful messages ?

[PurpleRain24]

Hi everyone hope someone can help I believe my mother has undiagnosed BPD. she also has a disability with her mobility  but refuses proper care and support. I left home at 3stil way a very unhealthy, abusive, codependent enmeshed relationship with my mother., went from no contact and  now having boundaries etc. Recently she has been really nice and I know she switches back and forth but it's made me think things could be okay and my boundaries lowered. Now I feel like a small child again with her treatment.
I still get scared when dealing with any confrontation as I know she will blow up and become really mean.  Most communication is via text as I feel safer that' way.
Yesterday she asked me to help her several times a month , to which I replied I can help but it wouldn't be that amount she is asking. ( for my own sanity and well being, as being around her is very emotionally triggering at times, and I still have allot of trauma from the house)
She was not happy with my reply and be and saying lots of horrible things like. (Comparing me to other ppls daughters, how she is all alone, suicidal and I made her feel worse, that she will do everything herself, I should collect my dad's ashes from her home, - mostly shaming, blaming, guilt tripping etc all via text and voice note.  My question is..
I'm still, unsure

What type of boundaries to set around it?

Can I ever make her aware of how she is acting?

After she calms down do I also just carry on as normal like she does?

 Does this mean I'm still accepting her bad treatment.

There will most likely be no accountability and whenever I do mention how she is being it makes things worse.
Mostly I just mute messages and try to be dicaplined not to keep reading them. Then I'll just write back short simple replies trying not to engage with all the hurtful things she is saying. But I'm not sure this is working. Every few months she will go into this message attack if I don't reply the way she wants. Any help is appreciated.

[Notwendy]

I have an elderly BPD mother. As far as accountablity- there is none on her part. Trying to talk to her about her behavior doesn't work and makes things worse. This limits the kind of relationship I have with her.

I don't live near her to be of direct assistance to her but I help in other ways- communcating with her medical providers, accounting (she's still in charge of her money- she's spent most of it).

Boundaries are on us, not the other person. We can not control anyone else. I have also heard the mean comments and accusations. We are so used to it we don't see it for what it actually is- verbal abuse.

It's taken some time for me to be able to have zero tolerance for it. I will leave the room, leave her house, get off the phone, turn the phone off. My boundary is how I behave, not how she does. I don't say mean things back, I am not rude, I simply excuse myself. I don't give a reason why- that is just more drama. Just say I need to go and leave or get off the phone.

I have done some work with 12 step coda and ACA groups ( they work for having a BPD parent too- not just alcohol issues) and counseling to work on my part- the feelings. I think we still have feelings- it's about how to help manage our own too.