Your claim the US is in a constitutional crisis because the president fired one of his appointees is simply absurd.

Even Comey acknowledged in an email to his staff that the president has the power to fire the FBI director for any reason or no reason at all.  Then, Comey wisely wrote this should be the end of it.

Either you don't understand the powers of a president or you are playing the cynical left wing game that Democrats who mere weeks ago were calling for Comey's head are now playing by claiming that this firing is terrible, unwanted and perhaps impeachable. 

Comey is not trusted by the president, his executive team or most members of congress on both sides of the aisle and must go.

Trump would have fired him weeks ago except for the delay tactics of the Democrats to thwart the hiring of Comey's boss the AG. 

And FBI inquiries don't grind to a halt just because the director (or anyone else) is replaced.

Trump deserves to have his own team and the time and chance to govern.