First of all, brutal loss. My condolences to your stack.
From your perspective, this is why not raising pre flop with faces is dangerous. If you’re late position and those three limped, I think a raise is mandatory to boot those mid range hands. If the 7,8 is suited, the agg player may come along regardless, so that might’ve yielded the same outcome.
When it checks to me on that board, I always throw a medium bet for info purposes. If anyone flats, I assume they have the top or bottom of straight draw. If they raise, I consider if it’s value for if/when they hit the draw or if I put them on trips. The turned Jack calls for a bigger bet, in my opinion, to shove off low pairs or those going for the draw.
Now the river prompts an all in from opponent. At that point, I assume this guy/gal just played his set covert somewhere along the way. Maybe they hit it with pocket queens, maybe they’ve had it since the flop. You’re against a straight or a set, in my mind, any time someone takes over aggression at all, let alone with a jam.
I feel for you. I slow played a flopped set last week when my opponent hit two pair on the flop. We both made a boat at the river, hers outdoing mine. However, in hindsight, I see my mistakes. I was in position, then at the river she takes over aggression with a pot bet. All I saw was my miraculous boat and snapped all in. Being that she’s my friend, she stopped and said, “I truly hate to do this to you, but I call.” Lessons learned, always!