You don't know the poster or his/her wife.
You don't know the wife.
You don't have anywhere near enough information (unless you think a BPD diagnosis or suspected diagnosis is in itself sufficient information, in which case you're contradicted by a very well established line of research going back a number of decades; see links I've posted elsewhere in this thread) to assess the poster's wife's mental state or likelihood of recovery.
Your comment completely misunderstands how BPD works and completely misrepresents the likelihood of recovery. I understand that you may need to prove to yourself that you made the right call by cutting off someone with this disorder in the past, and maybe you did -- but that isn't epistemic justification for the very conclusory advice you're offering the poster.