Former attorney general Sallly Yates apparently warned the white house that Flynn was in contact with Russia and was potentially compromised (ie blackmail threat etc)
Yates was fired but after some investigative journalism by the Washington post, it turns out that Flynn was in more contact with the Kremlin than he had let on and now he's gonna as well.

It'll be interesting to see how disgruntled Flynn is for being fired, as one article I read put it - he knows where ALL the skeletons are hidden.

This feels like politics from another era.