Don't Panic

Two lessons that I thought I knew, but didn't:
1. When an opponent makes an unexpected move, don't panic
2. Analyze until quiescence

In the positions below, I'm Black. In the first diagram, it's White to move. I'm in a little time trouble, but I think the game is basically even. I expect White to move b5, but he surprises me with Nxd5.

White to Move

r3r1k1/pp4pp/2p2pb1/3p4/1PnP2P1/2N1P3/P4PBP/R4RK1 w - - 0 22

After Nxd5

r3r1k1/pp4pp/2p2pb1/3N4/1PnP2P1/4P3/P4PBP/R4RK1 b - - 0 22

I've been working on my thought process, but the surprise made it go to pieces. My post-surprise thought process went like this:
Step 1. Panic
Step 2. "I always miss moves like that -- I always edit out captures of protected pawns"
Step 3. "If I take with the pawn, he takes with the bishop, forking my king and knight -- leaving him a couple of pawns up. Plus he's threatening to fork my rooks."

I didn't see any counter-attack, so I moved a rook, played on a pawn down, and eventually lost the endgame. Of course, if I'd calmly looked until the position was quiet, I'd have seen that I should take the knight with the pawn; if he recaptures with the bishop, blocking the check with my bishop also protects the knight, leaving me ahead a piece for two pawns.

You know, I didn't feel that bad after this loss, because it was such a good lesson for me. That's why it was important for me to start playing; you don't really learn until you learn it in a game. Actually, you don't really learn until you learn it in a loss.