I am guessing I played this hand terribly, so help me out guys. Flat or fold to 4bet pre? Flop plan as played?

Full Tilt No-Limit Hold'em, $0.50 BB (6 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

UTG ($76.60)
MP ($35.05)
CO ($72.60)
Button ($47.50)
SB ($139.95)
Hero (BB) ($50)

Preflop: Hero is BB with A, K
1 fold, MP raises to $1.75, CO calls $1.75, 2 folds, Hero raises to $6.50, 1 fold, CO raises to $11.25, Hero calls $4.75

Flop: ($24.50) J, 8, 2 (2 players)
Hero checks, CO bets $10, Hero??