Simply put - he’s worried because when Trump wins he will go to jail.
He emailed her under a pseudonym and doing so broke many laws.
Think back to his comments about saying “there’s classified and then there’s classified”. He will use this as his defense.
They will both be prosecuted by a Justice Dept that will do its job apart from Politics.
That is why he’s freaking out.
Bingo!
This applies to a lot more DC insiders as well with both Ds and Rs next to their names.
Every document produced by the POTUS is classified.