Bad turn raise? Should I be keeping customers?

CO had been raising for about 4-5 consecutive hands following a semi-bad beat; it seemed as though he was light on all tables I was on with him (~3), though he was a 12/8 or thereabout. I 3bet him here to cut off his range. I hit the perfect flop and the perfect situation with the unintended villain.

Full Tilt Poker $0.25/$0.50 Pot Limit Hold'em - 8 players - http://www.thehandconverter.com/hands/454754
The Official DeucesCracked.com Hand History Converter

MP1: $21.80
MP2: $15.20
CO: $51.55 - Frequent 3better on temporary tilt
Hero (BTN): $101.10
SB: $46.75
BB: $52.55 - Tight-"ish" player
UTG: $50.00
UTG+1: $68.55

Pre Flop: ($0.75) Hero is BTN with 6s 3s
4 folds, CO raises to $1.75, Hero raises to $4.25, 1 fold, BB calls $3.75, CO calls $2.50

Flop: ($13.00) 7h 4s 5c (3 players) -NEVER happens to me!
BB bets $3.50, CO calls $3.50, Hero calls $3.50 - Call behind because I want to keep both players in the hand. Given my pre-flop 3bet, if I raise here, the hand could be over for me. I don't think I'm getting all the money in with the current board state. I highly doubt this board improved anyone's pre-flop hand. I don't want to give information away about my hand, either; I could be floating (in position) with AK, which they've seen me do.

Moreover, not that I am worried about a set, but in the unlikely event of a stubbornly played pocket pair / flopped set, I want to ensure that the villain will be drawing thin to the turn. Although this is the perfect flop for me, I don't want to box myself into the hand - particularly when my opponents are clearly interested and putting money in. In other words, I think I can still get away from this hand, given the turn betting texture & actions. I am working to semi-contain pot sizes at this early stage of the hand.

Turn: ($23.50) Qc (3 players)
BB bets $8.50, CO calls $8.50, Hero raises to $20, BB raises to $31.50, CO folds, Hero raises to $93.35 all in, BB calls $13.30 all in - Here is the question: Should I have raised here? I figure that if I flatted the turn, I'd have 2 people in the pot going to the river, with $49 in the pot. I believe the CO would be calling a "reasonable" river bet of $15-20, since he's sandwiched in the middle of us. I think a flat would have netted me a $140-150 pot instead of $121, but is it worth it to carry an extra player to potentially suckout on me? For what it's worth, I put the CO on a hand like 88-TT.

River: ($121.60) 2s (2 players - 2 are all in)

Final Pot: $121.60
Hero shows 6s 3s (a straight, Seven high)
BB shows Qd Qs (three of a kind, Queens)
Hero wins $118.60
(Rake: $3.00)