I think your use of the term “bitter” with regard to T. S. Eliot’s response is to prejudge too much: There are of course many questions raised by Eliot’s statement, but “bitter” seems too categorical to me, at this stage of the critical reception and evaluation of the letters and their contexts. It is now an historical document, and one’s first contemporary reaction — in this case, “bitter” — might need to be more closely fine-tuned when the times and the circumstances are properly evaluated.
Also — perhaps more importantly — you write that Eliot “asserted” that he and Emily Hale had never had sexual relations. “Asserted” implies that the question may be open to dispute and disproof, but do you have any reason not to believe Eliot? “Eliot stated” might be nearer the mark.