Party, $0.25/$0.50 No Limit Hold'em Cash, 6 Players
BB: $50 (100 bb) 17/10/1.9/4.7/3.7 [VPIP/PFR/AF/3bet/4bet-range]
MP: $45.04 (90.1 bb)
BTN: $51.30 (102.6 bb)
CO: $105.30 (210.6 bb)
Hero (SB): $61.88 (123.8 bb)
UTG: $50 (100 bb)
Preflop: Hero is SB with K♣ K♠
UTG folds, MP calls $0.50, 2 folds, Hero raises to $2.50, BB raises to $6.50, MP folds, Hero raises to $15, BB calls $8.50
Flop: ($30.50) 2♦ A♠ T♥ (2 players)
Hero bets $15, BB raises to $35 and is all-in, Hero folds
Results: $60.50 pot ($3 rake)
Final Board: 2♦ A♠ T♥
BB mucked and won $57.50 ($27.50 net)
Hero mucked K♣ K♠ and lost (-$30 net)
I had little RL issue to quit the session quick, but got into this hand at the end. My Cbet size is somehow weak. Should have pushed or ck/fold it I guess. Another mistake here is bet/fold line... 
His flop pushing range could be:
Board: 2♦A♠T♥
Equity Win Tie
MP2 48.65% 46.46% 2.19% { KK }
MP3 51.35% 49.16% 2.19% { TT+, AKs, AKo }
Preflop 4bet range:
Board: 2♦A♠T♥
Equity Win Tie
MP2 52.73% 51.12% 1.61% { KK }
MP3 47.27% 45.66% 1.61% { 99+, AQs+, AKo }
But now yes, my 4bet is way to strong and I don't have much more room for any postflop play, like you pointed out.