Oops

I'm playing in the 30th Collyer Memorial Chess Tournament this weekend. The event usually draws 60-70 players and is the largest and strongest event in my city. This year's is the last for this event and we have 110 players. The TD is using accelerated pairings, something new this year. I managed to win my first round game against a player whose rating is rising fast. It took me 80 moves and required understanding of Philidor and Lucena rook endgame positions. At one point in the game, however, I blundered and gave him a chance to win.

Black to move

What should he have played?