Comey is not tRump's attorney.
He was the Director of the FBI.
I don't see any attorney - client privilege/confidentiality there.

he deliberately wrote the memos so that they would be unclassified.

http://www.slate.com/blogs/the_slatest/2017/06/08/trump_s_lawyer_suggests_james_comey_broke_the_law_he_didn_t.html
<snip>
Here’s the relevant exchange between Comey and Sen. Mark Warner:

Warner: You made clear [in your prepared remarks] that you wrote that memo in a way that was unclassified. If you affirmatively made the decision to write a memo that was unclassified, was that because you felt at some point the facts of that meeting would have to … be shared with the American people?

Comey: Well, I remember thinking, This is a very disturbing development. … If I write it in such a way that I don't include anything that would trigger classification, that would make it easier for us to discuss within the FBI and the government and to hold on to it in a way that makes it accessible to us.

Comey did mention on Thursday that he had one classified conversation with Trump, but that it was unrelated to the Russia investigation and “was brief and entirely professional.”

But I did hear a lawyer say today....That even if they were privileged conversations, Trump broke that privilege when he, himself tweeted about them. So nice try kaskowitz.

say that he did it as a private citizen, after he was fired, not as director of the FBI. In addition, it wasn't classified material. He is not the equivalent of Julian Assange.

The right will attempt to smear him nonetheless.

Trump's Lawyer is so out to lunch that he won't be back in this lifetime.

Once you are fired even without cause,those so called confidential agreements go bye bye. Been down this friggen road.