I didnt know what to do so I checked the river in EP

***** Hand History for Game 2003702329 *****
$100 NL Hold'em - Thursday, May 05, 16:41:08 EDT 2005
Table Table 37542 (6 max) (Real Money)
Seat 2 is the button
Total number of players : 5
Seat 3: SlappYou ( $143.45 )
Seat 6: upmysleeveKK ( $85.4 )
Seat 4: AKdevil ( $124.15 )
Seat 1: thequad ( $97.3 )
Seat 2: thumpin347 ( $36.28 )
SlappYou posts small blind [$0.5].
upmysleeveKK posts big blind [$1].
** Dealing down cards **
Dealt to SlappYou [ Jc Ks ]
Mach1fan has joined the table.
thequad raises [$2].
thumpin347 folds.
SlappYou raises [$3.5].
upmysleeveKK folds.
thequad calls [$2].
** Dealing Flop ** [ 5h, 3h, Jd ]
SlappYou bets [$8].
thequad calls [$8].
** Dealing Turn ** [ Th ]
SlappYou bets [$20].
thequad calls [$20].
** Dealing River ** [ As ]
>You have options at Table 36696 (6 max) Table!.
SlappYou checks.
thequad bets [$40].
SlappYou folds.
thequad does not show cards.
thequad wins $103


The pot was $60 and then the worst possible river card came...

I thought about betting a half the pot but that would have been too much into a flush board, straight board, and A board. I knew he had to be calling me with some sort of an ace at the minimum, and my hand wasnt huge. I knew that checking on the river could have induced a bluff, but his bluff was too much for me. Where would you have done this different?

Nothing..you are betting the pot every street and he just keeps coming...he either had you, or passed you on the river. nice job not paying him off on it.