Unraised pot, two pair on the river facing huge raise

[insyder19]

Okay I don't know if a fold is the best advice here, I guess so but how often are we getting bluffed in this spot?

Titan No-Limit Hold'em, $0.25/$0.50BB (Titan HH Converter by Kreatief)

MP3 ($54.90)
CO ($50.75)
Button ($51.80)
SB ($54.74)
BB ($48.50) (Hero)
MP2 ($50.75)

Preflop: Hero is BB with A[img]/images/graemlins/spade.gif[/img], 7[img]/images/graemlins/diamond.gif[/img]
MP2 calls $0.50, <font color="#666666">1 folds</font>, CO calls $0.50, <font color="#666666">1 folds</font>, SB calls $0.25, Hero checks,

Flop: 3[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/heart.gif[/img], J[img]/images/graemlins/spade.gif[/img] ( $2 )
SB checks, <font color="#CC3333">Hero bets $1.50</font>, MP2 calls $1.50, CO calls $1.50, <font color="#666666">1 folds</font>,

Turn: A[img]/images/graemlins/diamond.gif[/img] ( $6.5 )
<font color="#CC3333">Hero bets $5.00</font>, MP2 calls $5.00, <font color="#666666">1 folds</font>,

River: Q[img]/images/graemlins/spade.gif[/img] ( $16.5 )
<font color="#CC3333">Hero bets $7.50</font>, <font color="#CC3333">MP2 raises to 28.0</font>, Hero calls $20.50,

Final Pot: $69.50