You might want to read and bookmark this article from the American Enterprise Institute. This is why the Obama Insiders, Clapper, Brennen, Rice, et all, hated Flynn so bad and he was the first casualty in the Trump Administration. Combine this article with the one about this FBI agent and you can see why the FBI wanted Flynn out.... BADLY.
http://www.aei.org/publication/the-real-source-of-team-obamas-despair-over-mike-flynn/