Standing up to a narcissistic big sister

"and how your life should contain only those who can respect, love and care for you. And she’s not one of them."

This really helped - thanks for writing that Grandmafrench

Thank you all. It's so tragic, I'm really only in contact with her because her adult child was killed...I feel huge sorrow for her everyday.

Why would you continue to allow anyone to treat you so badly? Three times in your post you say she terrifies you. That’s awful but you see her ‘regularly’ even though she clearly has no decent feelings or she would never treat you in the way that she does. Racked with jealousy over her Sister’s life, a cruel bully, a narcissist? Who knows? But after all this time why on earth would you care? She’s lost the right to have any sort of contact with you, cares nothing for your own sadness, just wants you to be under her control where she can mistreat you, lie and abuse you as and when. Best thing is for you to cut contact. This is not a trivial family fallout - this woman has form, and will continue to spoil your life if you allow it. Very little chance of her changing her behaviour after so many years, so you need to toughen up and think of yourself now and how your life should contain only those who can respect, love and care for you. And she’s not one of them.
Ignore and maintain a silence. Let her distress someone else. She may need help, but not from you. Don’t spoil even one more day feeling guilty, because you have nothing to feel guilty for.
So sad you’ve lost your little cat. Take care, stay strong and I wish you happy times.

I agree too and suggest absolutely minimal contact, ie dont initiate, reply politely but not getting dragged in, live your own life.

However, guilt is a heavy burden, I don't cope brilliantly in that tho its not about family.

Perhaps others here have better advice from me as regards
guilt in these circumstances.

Agree with the above. I would start by reducing contact by not messaging her. If she messages answer in a polite way without inviting a reply.

I see, thank you both

You will never win.

Agree.
No point even trying to.

It doesnt sound to me like you need to have guilt about what you have done.
But I cant judge you or her.

I’m afraid the only way to deal with a narcissist is to go no contact.

My mother was a classic narcissist and my father a complicated one so I feel fairly well qualified to advise.

You will never win.