BB: 240 BB
Hero (BTN): 120 BB
SB: 115 BB

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has J J

Hero raises to 3 BB, SB calls 2.5 BB, BB raises to 12 BB, Hero calls 9 BB, SB calls 9 BB

Flop: (36 BB, 3 players) 5 Q J
SB checks, BB checks, Hero bets 18 BB, SB calls 18 BB, BB calls 18 BB

Turn: (90 BB, 3 players) 2
SB checks, BB checks, Hero bets 46 BB, SB calls 46 BB, fold

River: (182 BB, 2 players) A
SB bets 39 BB and is all-in, Hero calls 39 BB

SB shows K T (Straight, Ace High)
(Pre 29%, Flop 26%, Turn 18%)
Hero shows J J (Three of a Kind, Jacks)
(Pre 71%, Flop 74%, Turn 82%)
SB wins 251 BB

I'm almost never folding here. He's going to have to shove any card on the river, and you're going to have to call almost any card on the river, especially with no flush draws. I would hide the result just for people to think about the hand without influence. Although this is one case where I don't think it matters at all.

I think the turn is the real question mark- You're betting half pot- I'm probably jamming just because of SPR and now that there is a flush draw on board, as well as the flopped straight draw potential. I think any 2 pair, set, maybe AQ, KJ, is calling it. I think the turn bet sizing is what I question- I'll try and think about it more but first look it looks like a great spot to jam for value.

No, also why are we just flatting JJ pre? I would probably just 4b or jam this spot.

Stop posting results.
How can I think seriously about the hand when I know villain rivered the nuts and has you beat?

But no, you can't fold.
Could be AK, AQ, AJ, 55, ...

I would play it very similar.

Just cbet 1/3 on the flop tough and bet 3/4 on the turn or all in for protection.

I am on my phone so can't look at GTO Wizard's ranges right now, but I think JJ is either pure or near pure as a 4bet pre. I would just always 4bet it. Getting heads up with the BB and creating dead money is nice. Plus 3handed poker gets crazy, so JJ is extra nice here.

I would bet small on the flop, maybe like 9-10 BB. As played, i probably go smaller on the turn though sizing doesn't matter a ton here. BB played pretty weird by checking flop and calling the turn without odds. Gotta call river of course. The price is fantastic. He can have AK, AQ, AJ, maybe an occasional spazout.