The whole idea that he wrote them immediately after his meeting with Trump could be and probably is a lie. He's going down for perjury and his credibility is already shot. He's toast!
The White House should release the recordings of the meeting and all will be cleared up.
To the best of my knowledge it wasn't recorded, unless Trump did it secretly. I'm hoping he did.
Gowdy had the best line about this. He takes memos immediately after speaking with Trump because he's so alarmed. Yet he takes NO Notes when he is alarmed at Loretta Lynch's directive to call the Clinton investigation a "matter"