For better or worse, because of Omaha Poker River strategy you know exactly what you have and you know what the best possible hand is. Given what has happened previously you should know what you are up against. Miscalculations here have been responsible for many online poker games witnessing players leaving the room kicking and screaming.
The way you play it depends on the strength of your hand, the size of the pot, the amount of players still in the hand and what the online poker strategy suggests. If you are unsure as to the strength of your hand given your opponents, checking may be a good way to go or think back to what Omaha Poker river strategy advises you to do.
If you are sure you do not have the best hand and other players bet strong then fold unless you believe he is bluffing and your hand is close enough to the best possible hand to still win.
Given that you may also check if you intend to check-raise, that means your online poker opponent may be none the wiser about your hand.