Middle pair vs. a river bet?

[bwolf4]

No real reads on villain. Seems TAG. Just doubled up with KK on a 235 board when a guy called with J3o.

Full Tilt Poker, $0.05/$0.10 NL Hold'em Cash Game, 5 Players
LeggoPoker.com - Hand History Converter

BTN: $1.40
SB: $10.20
BB: $5.50
UTG: $5.10
Hero (CO): $6.90

Pre-Flop: A[img]/images/graemlins/club.gif[/img] T[img]/images/graemlins/spade.gif[/img] dealt to Hero (CO)
<font color="red">UTG raises to $0.20</font>, Hero calls $0.20, BTN folds, SB calls $0.15, BB folds

Flop: ($0.70) 3[img]/images/graemlins/heart.gif[/img] 5[img]/images/graemlins/heart.gif[/img] T[img]/images/graemlins/heart.gif[/img] (3 Players)
SB checks, <font color="red">UTG bets $0.20</font>, Hero calls $0.20, SB calls $0.20

Turn: ($1.30) 8[img]/images/graemlins/club.gif[/img] (3 Players)
SB checks, UTG checks, <font color="red">Hero bets $0.60</font>, <font color="red">SB raises to $1.20</font>, UTG folds, Hero calls $0.60

River: ($3.70) K[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">SB bets $2</font>

Hero?