[Mathieu]

I think check calling this river would be a mistake. You are most likely ahead here. As others pointed out, most players would have raised you on the turn with a made straight or flush. Value betting was a good idea since your opponent would have likely called with a weak made hand that wasn't worth a bet. If you check he will mostly bet hands that have you beat. This is important, most of your opponents at 0.5/1 call too much, and you have to exploit this weakness.

Bet/folding this river is a big mistake. You are given 8-1 on you're call! Your opponent might have spiked a K and decided that it was worth a raise. Maybe he had overcards with 1 diamond and is bluffing a busted draw. You only need to be good 11% of the time here, and I think you will win much more that.