Straight Flush = Fold?

Based on the preflop, flop and turn action, I read his hand as AK or KK with the king of diamonds. Did I make a wizard fold, or am I an idiot?

Full Tilt Poker No-Limit Hold'em, $1.00 BB (9 handed) - Full Tilt Poker Hand Converter from HandHistoryConverter.com
SB ($100.50) BB ($182.35) Hero (UTG) ($105.60) UTG+1 ($95.85) MP1 ($100.50) MP2 ($104.50) MP3 ($92.30) CO ($53.50) Button ($117.95)
Preflop: Hero is UTG with 9, 8
Hero bets $2, UTG+1 raises to $5, 7 folds, Hero calls $3
Flop: ($11.50) Q, A, 10 (2 players)
Hero bets $5, UTG+1 calls $5
Turn: ($21.50) 3 (2 players)
Hero bets $15, UTG+1 calls $15
River: ($51.50) J (2 players)
Hero bets $1, UTG+1 raises to $70.85 (All-In), Hero folds
Total pot: $53.50 Rake: $2.65
Results:
UTG+1 didn't show
Outcome: UTG+1 won $50.85