When you are under pressure, it is good to trade off pieces. He is trying to trade queens, thereby ruining my attack.

!! Castling queenside gets the king to safety, brings the rook into action and checks the white king.

This is his only legal move.

Now I can trade queens because Bc3xe1 Rd1+ wins the e1 bishop.

Had to lose the knight but will get the material back later.

! The bishop cannot take because it is pinned to the rook.

?? A desperate attempt to disrupt my pawn structure.

There was no way he could defend his bishop so he might as well get something out of it by taking my bishop. He will lose the rook now, of course.

Preventing the rook from capturing the pawn.

Developing my last piece so that my other rook can get out.