I realize now that white had this sac in mind in case of e5 since long ago, and this is why I am more than -200...  .

Somewhat ironically, given White's opening, he now has exclusive rights to the d5-square, and a light-square vulnerability is starting to be felt on Black's K-side as well. The pressure on the central dark squares acts as a kind of echo to the more immediate blow to the light squares.

In sight of this, it seems that the fiachetto's plan wasn't bad, after all. I wonder how would it be having black closed the diagonal before the knight's sac was possible.

I like this move.

First thing I thought of in this position, though I wasn't absolutely sure White would play it. Black's position is starting to look like the U-47 at extreme depth, its conning tower subjected to extreme pressure and about to implode.

Was it the bishop's move the best choice? I wonder how about c4, sacrificing another pawn but opening a nice square for the dsb. And why was the bishop preferable to the knight? From e6, the knight can jump to d4. After it, Bd6 helps control c4 for a pawn advance, if allowed.

The depth charges just keep coming!

And naturally, allowing White a huge centre after 18...Nxd5 19.exd5 is out of the question.

Provided black accepts not to castle, Ba7 would have made up for a future c4.

Kh8, to try to losen the force of Nf6.

Yep: there was some choice in the build up moves, but this one's pretty obvious. Nothing else comes into consideration, really. The Knight must be taken, whereat White's attack will smash through the K-side, the defenders all cut off.

The knight has to be taken as King and Queen are forked