Double AA

The chance that hes got a flush is quite decent since you have top set and what is he supposed to have but 66 and 88 that he's capping. 66 and 88 are just 6 combos and strongly outnumbered the flush combos and without the flush on the Turn its questionable whether you should 3bet but with additional outs to nutflush and top boat it should be an easy 3bet. You have just 30% Equity due to your outs so its ok when there is an overlay of flushcombos to worse ones like 33 66 88 68 A6 A8 Ax in general or maybe KK QQ with :diamond:. 3bet is pretty clear but after his cap it was the right decision not to give more action but just c/c the River. Well played!

wp

Versus a more untrustworthy super-aggressive, but not suicidal, opponent, there is a fishy play that might be an alternative. Suppose you think that you are still ahead going into the river, but you think that if it goes to 3 bets, then you are screwed. Then a river donk-call may have the best EV. The rationale is that you can't possibly check-raise-fold with top set, yet you will get two bets in on the river if you have the best hand. It does require a special type of opponent, and is mostly just an exploitative thought.