send her a message saying that sometime after she initiated the silence between her and you, you found out that silence is just what you need from her

My only concern here is that I feel like we are in a power struggle – I know without a doubt that she is being coached by a very mentally unwell friend to not ‘give into’ me (=any communication), – so I almost feel like if I send a message she will feel like she won. I don’t know, maybe it doesn’t matter?

and let her know that if she initiates contact with you before that further notice, you will not respond to her

and please entlighten me if I am off base, but I kind of see this as doing the same thing as she is doing to me?

I would never give her the silent treatment, with each day I just can’t understand she has turned into this kind of person.