Could've sworn I wasn't playing on Party...

[Wired Jokers]

Three-bet the river. What are you afraid of here? Your opponent does not have 3,4, unless he is totally insane. (he raised pre-flop). My guess is that he rivered his two pair, AQ.

If he's got AA or QQ, then so be it. But QQ is not as likely, since he did not cap the turn nor did he raise the flop. Anyway, losing to set over set is nothing to be ashamed of.