If you're going to down bet flop then give up I would rather not 4 bet this hand. We should only be building a pot with hands we are comfortable going to war with. If this guy is squeezing 52s we are still ahead of a good portion of his range on this river given our small flop sizing and turn check back. As played I probably check turn and call river.
Alternatively we can flat the 3 bet and call flop. If HJ comes along both pre and flop we can probably fold to the turn double barrel. AP once we 4 bet (and I do prefer a 4 bet here) I agree we should size to $40 or so pre. $25 is fine on the flop. x turn, call river. If this guy had an Ace or a flush draw I think he would be piling in money on the flop. We are still behind Qx, some weird two pair hands, and a slow played monster but from the description I'm not sure this guy slow plays much at all. Like you said, he saw us show weakness checking back turn and snap bet large on the river. He could have 7x, 5x, 3x, some other under pair, or air here quite often.
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