She says "when we get this we are both going to die. She finds it inevitable." I don't know how to to answer
Oh dear. When my mom says stuff like this it always catches me off guard, and my brain kind of "freezes" and I can't think straight.
As someone else said, I think the best approach is to meet her at her emotional level, and so validate her feelings. I think BPD's tend to exaggerate to the negative (my mom has always been like this), so people mom knows are always at death's doorstep. They never die when she says they will.
So maybe something like: "These are scary times with Covid 19. It is a good time for everyone to take reasonable precautions and stay safe. I think lots of people are worried like you are."
Maybe a validating question such as "What are you and dad doing to stay safe these days?" even if you already know the answer (since she's already a clean freak). But asking the question may elicit several answers, which may give her a feeling of control, which could be helpful.
My uBPD mom is 83 and scared too. So are all her friends. All of them have health conditions which compromise them. They are all self-isolating.
These are scary times.
I just do the phone version of a nod which is saying "uh-huh".
Especially when she catches you off-guard, right? But I would be careful against validating her fear that she is going to die. Validating the feeling of "fear" of an invisible enemy, is different than validating the belief that her life is about to end. I think we are all a little fearful these days.
On a happier note, there are actually cases of a 99 year old and 101 year old (and others) who survived coronavirus. I wouldn't tell her that as it would
invalidate her fear, and right now it's most important to
validate her. If she accepts the validation and settles her emotion in a few days or a week, maybe she could "discover" those news stories on her own later. Regardless, it's kind of nice for the rest of us to hear those stories too.