$1/$2 5/6s deep stacked, am I on trouble on the flop?

[Bluegrassplayer]

SB is a very LAG player, more often dumping to the table than not. UTG +1 is a very solid TAG player, and the cut off is a semi-solid player who plays a lot of mediocre hands when he gets deep stacked in the hope of cracking a big stack.

SB: $225
BB: $195
UTG: $200
UTG+1: $285
5 Seat: $155
6 Seat: $55
CO: $475
BTN (You): $695

Preflop: You are dealt 5 [img]/images/graemlins/diamond.gif[/img] 6 [img]/images/graemlins/diamond.gif[/img]
UTG folds, <font color="red"> UTG +1 bets $12 </font>, 5 Seat folds, 6 Seat folds, <font color="red"> CO calls </font>, <font color="red"> You call $12 </font>, <font color="red"> SB calls $12 </font>, BB folds.

Flop: ($50) 7 [img]/images/graemlins/diamond.gif[/img] 9 [img]/images/graemlins/diamond.gif[/img] A [img]/images/graemlins/spade.gif[/img]
<font color="red"> SB bets $35 </font>, <font color="red"> UTG +1 calls $35 </font>, <font color="red"> Co calls $35 </font>

You do what? Now this is a very unusual circumstance at our game. SB is capable of betting with anything, but when UTG +1 calls, I'm almost sure that they are sharing aces, with UTG having a much better kicker. I have no idea what the cut off has. It's possible he has a straight draw, or a higher diamond draw, so I'm at a loss as to what to do here. What actually happens is that I get time called on me and end up putting in $35. Now the turn is a great card for me, making my decisions much easier, so I'd like the biggest amount of criticism/ input for this street.

<font color="black"> Turn: </font> ($190) 6 [img]/images/graemlins/club.gif[/img]
<font color="red"> SB bets $60 </font>, UTG +1 says he knows he has the SB beat, but has no idea whats going on behind him and folds. <font color="red"> Co calls </font>,

hero does what?

Almost certain that the CO has diamonds now, if he was chasing any straight draws, he almost certainly hit, and he would definitely have pushed. The weak bet from the SB also makes me convinced that he's playing a weak ace, certainly not 2 pair so the turn gave me 5 additional outs. What do I do here?