J8s 3bet oop

You have to 3 bet bluff for a reason. J8s is ok for that purpose in these positions.
I do not see a reason to bet turn.

Hey Tzoun, yeah definitely fold the J8s in the small blind. You can play very tight at NL5 when you are still learning, people generally don't like folding and the rake is large so there's no reason to play marginal hands like this one

If he's been stealing your money too much and you REALLY want to 3bet him a lot in the small blind wide vs a player like that at the limit, do it with e.g. TT+, A2s+, K9s+, Q9s+, J9s+, T9s, 98s, 87s, 76s, ATo+, KJo+ so you flop a lot of hands. And unlike in the BB you have less incentive to call. so you can just 3bet or fold the small blind, and just call the 22-77, people won't notice, promise

Postflop is meh, but I'd either check fold flop (you have to do that a lot more if you decide to play wide ranges like that) or just give up on the turn.
But really best is at these stakes to follow the tight strategy with which you can cbet a lot as your preflop ranges are stronger - and the flop spot is just a function of your too loose preflop play