Who leaked Ford's letter

There were only a limited number of people who knew about Ford's letter: Ford herself, Anna Eshoo, Dianne Feinstein, their staffs, and any legal counsel Ford had retained.

If Eshoo, Feinstein, or anyone on their staffs leaked the contents of the letter, then, they behaved in a manner utterly inappropriate for elected officials, sharing the contents of the letter with the media, but not with their Republican colleagues on the Judiciary Committee.

On the other hand, Feinstein maintains that Ford's charges were not leaked by her or her staff, but by Ford herself:

It’s my understanding that her story was leaked before the letter became public. She testified that she had spoken to her friends about it and it’s most likely that that’s how the story leaked and that she had been asked by press. But it did not leak from us, I assure you of that.

But, if Ford herself was openly discussing the letter with friends, then, Feinsteins's entire justification for withholding the letter from her Republican colleagues, namely, her sacred obligation to honor Ford's request to keep the letter absolutely confidential, evaporates. What need was there for Feinstein to maintain strict confidentiality about the letter if Ford herself was openly discussing the matter with her friends?

If Feinstein's explanation of the sequence of events is accurate, then what likely happened is: when the existence of the letter was not having the desired effect of derailing Judge Kavanaugh's confirmation (presumably because of the total lack of corroborating evidence), Ford's circle leaked the contents of the letter to the press in order to bring the smear out into the open so that it could be pushed by sympathetic media outlets.

In other words, if Feinstein's explanation is correct, then Ford lied about her absolute requirement for confidentiality, just as she lied about her fear of flying.