Slowplay?

[MagicFlea]

No reads. Actually a full ring table, but only 4-handed

Party Poker 5/10 Hold'em (4 handed) converter

Preflop: Hero is UTG with 9[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/spade.gif[/img].
<font color="#CC3333">Hero raises</font>, Button calls, SB calls, <font color="#666666">1 fold</font>.

Flop: (7 SB) 8[img]/images/graemlins/spade.gif[/img], 8[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, Hero checks, Button checks.

I rarely slowplay... I thought this might be a good situation, as a free card could give a straight. In hindsight, suspicious since I raised PF.

Turn: (3.50 BB) 7[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets</font>, <font color="#CC3333">Hero raises</font>...

I can't afford not to raise here, even with a potential caller since he might have hit a straight, in which case I've run into a goldmine. thoughts on the slowplay and turn raise plz.