This is a categorically dual relationship malpractice issue.

You were a client of Kelly’s for 1.5 years yet Kelly stepped into a *highly* intense ritual retreat with a dual relationship, the depth of it unknown.

This means that her entire experience is coloured by monitoring for your performance as a former client.

This is a huge problem. I can't see an ethical way for her to include her experience in this letter.

(fwiw, I have no opinion on the actual critique and I can see maybe there were learning moments but that doesn't mean the severity is a good reflection)