[p@t@dds]

I think you should bet out on the turn here. If "button" has an ace, he will most likely raise and you can dump your hand or call and then check/fold on the river if you don't improve. No need to give him a chance to catch a free card on the river if he doesn't have an Ace. Granted a 5 came on the river, but during the hand you have no idea what cards he is holding. If he has any King or Queen he could outdraw you by spiking one, he could be drawing to a flush or a gut-shot wheel, or worst of all he could have pocket 5's. A bet here, might get him to fold before that 5 pops up on the river. I think betting out on the turn will give you more info about his hand and if you plan to fold to a raise it will cost you less than check/calling to the river. That's just my opinion. Hope it helps.