Mrs A sending you hugs. I am quite horrified your sister talks to you in this way.

It sounds like what she is doing is technically known as triangulation. It's when someone tries to involve others (who aren't directly involved) in order to back up their points. Usually because their own standpoint is very weak and shaky. So I would say please be aware of this. She is likely deep down very insecure.

It leaves you however with the aftermath of her words, and sticks and stones may break our bones but words sadly do hurt us.

I don't know your sister. Is it possible if in a calm moment if you sit down over a coffee and say "It hurts when you say that... (whatever phrase she used)" that it will prick her conscience? Or is she the type who will derive pleasure from knowing she hurt you even in a calm moment?

It's a judgement call from you who knows her best of all.

In the meantime, my sincerest well wishes to you- you deserve better.