so i guess this is considered a "defensive bet" <-- quotes , and if it isnt then im clueless but i mean is this just stupid and not optimal? pretty sure hes calling my bet with an ace and im sure hes gonna bet it so i figured i should bet and he might just call if he doesnt have an ace cause the only thing he should be raising me with here is a straight, otherwise my decision is alot harder check calling or check calling, waht do you guys think ? thanks

Full Tilt Poker, $5 + $0.50 NL Hold'em Sit n' Go, 25/50 Blinds, 5 Players
LeggoPoker.com - Hand History Converter

UTG: 980
CO: 1,635
BTN: 1,755
SB: 2,530
Hero (BB): 2,100

Pre-Flop: (75) J T dealt to Hero (BB)
2 folds, BTN raises to 100, SB folds, Hero calls 50

Flop: (225) J 3 5 (2 Players)
Hero checks, BTN checks

Turn: (225) 2 (2 Players)
Hero bets 175, BTN calls 175

River: (575) 4 (2 Players)
Hero bets 125, BTN raises to 550, Hero folds

Results: 825 Pot
BTN mucked and WON 825 (+425 NET)

I think your bet was way too small,but hes probably 90% not bluffing also. Bet 200 and its good i guess. C/F is also an option i guess.

Villain has an ace here like 99.9% of the time.

Bet like 150 on flop, bet 1/2 pot again on turn.

c/f river as any ace is a huge part of his range here.