No, Mary does not get a lifetime pass to do anything to Edith because she told about Pamuk. No, everything she does is not fair payback. After awhile the statute of limitations has to run out on Edith not being an innocent victim of Mary’s vitriol. Edith is not under a lifetime sentence of having to pay for what she did.
I know it’s silly to put this under spoilers, because people have already posted in detail what happened this episode. But, I just can’t bring myself to do it, when it hasn’t aired in America yet.