$50 Conflicted w/overpair on terrible board

[NLHE lahooozaher]

Villain is 15/5/1.00 after a ~150 hand sample. No hands stand out, no history, and this is my first hand at the table. I usually raise this preflop to $3 but for some reason this table didn't pop up when it was my turn and my timebank was almost gone so I did $2.50.

On the river I'm conflicted because it seems I'm only losing to 78(double gutter on flop) and a slow played set but sets probably raise flop or turn. On the other hand he only has an AF of 1 but I haven't got a great sample for that. So what it do?

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

UTG ($69.85)
MP ($74)
CO ($32.50)
Button ($14.40)
SB ($55.80)
Hero ($50)

Preflop: Hero is BB with Q, Q.
1 fold, MP calls $0.50, 1 fold, Button calls $0.50, 1 fold, Hero raises to $2.5, MP calls $2, Button calls $2.

Flop: ($7.75) 5, J, 9 (3 players)
Hero bets $6, MP calls $6, Button folds.

Turn: ($19.75) 8 (2 players)
Hero bets $12, MP calls $12.

River: ($43.75) 6 (2 players)
Hero checks, MP bets $19, Hero

[Ash256]

I like valuebetting river, as played you have to call.