Jacks in the SB. Pain and suffering

[rewt75]

only have played about 25 hands with MP2. VPIP at 14%, PFR 3.7%, AggTot 4

Party Poker 0.5/1 Hold'em (8 handed)

Preflop: Hero is BB with J[img]/images/graemlins/club.gif[/img], J[img]/images/graemlins/diamond.gif[/img].
UTG calls, UTG+1 calls, MP1 folds, <font color="CC3333">MP2 raises</font>, CO calls, Button calls, SB folds, <font color="CC3333">Hero 3-bets</font>, UTG calls, UTG+1 calls, MP2 calls, CO calls, Button calls.

Flop: (18.50 SB) J[img]/images/graemlins/heart.gif[/img], 5[img]/images/graemlins/heart.gif[/img], 3[img]/images/graemlins/diamond.gif[/img] <font color="blue">(6 players)</font>
Hero checks, UTG checks, <font color="CC3333">UTG+1 bets</font>, <font color="CC3333">MP2 raises</font>, CO calls, Button folds, Hero calls, UTG folds, UTG+1 calls.

Turn: (13.25 BB) 4[img]/images/graemlins/diamond.gif[/img] <font color="blue">(4 players)</font>
Hero checks, UTG+1 checks, <font color="CC3333">MP2 bets</font>, CO folds, <font color="CC3333">Hero raises</font>, UTG+1 folds, MP2 calls.

River: (17.25 BB) 2[img]/images/graemlins/spade.gif[/img] <font color="blue">(2 players)</font>
<font color="CC3333">Hero bets</font>, <font color="CC3333">MP2 raises</font>, Hero calls.

Final Pot: 21.25 BB

My intention was to keep as many of these people in the pot as possible on the flop, then C/R the turn. Fortunately someone raised ahead of me so I...well I inhaled a fresh batch of seawater in through my gills and called. I'm normally aggressive and would've had no problem 3-betting, but I was trying to be sneaky.

How bad is the river bet/call?