As to the first, NO. Confidential means you don't tell anybody.
As to the second, sure there was a leak to the press. It was likely either a staffer of Feinstein or of Anna Eshoo's office. Whether it was a staffer who did it on his or her own initiative or at the direction of Feinstein or Eshoo is unknown. Everyone involved theoretically had a motive. These kinds of leaks happen both ways. Trump's WH has had staffers leaking information to the press without his direction since the beginning.
What I don't agree with is conservative media, which I've been reading this morning, criticizing a decision to withhold a letter the author of which requested confidentially. I just read a lengthy piece on Fox News quoting lots of these criticisms and not once even mentioning the confidentiality request.