Live $3/$5 hand

[bilbo-san]

Hero has $580
CO has $520
Button covers us

CO is a very loose and pretty aggressive player who seems to sort of know what he's doing postflop, but limp-calls way too much preflop. From a relatively small sample size my read is that he leads into PFRs with strong hands.

Button is a little too loose preflop, doesn't quite understand the dangers of dominated hands, and overplays good but not great hands postflop (i.e. doesn't understand concepts like being ahead of the calling range to make raising ok). He's not a complete fool, though, and can lay down a hand if it's obvious he's beat.

Hero limps in EP with 2[img]/images/graemlins/club.gif[/img]2[img]/images/graemlins/diamond.gif[/img], MP limps, Button makes it $20, BB calls, I call, MP calls.

Flop A[img]/images/graemlins/diamond.gif[/img]2[img]/images/graemlins/heart.gif[/img]4[img]/images/graemlins/club.gif[/img]
BB checks, I decide the A is tempting enough to go for the C/R because BB might call if button bets a big Ace, MP surprises me and bets $45, Button makes it $100, BB folds, Hero...?

calling, raising, and pushing all seem to be bad because they give away my hand. At this point I hate that I did not lead. Then again, if the board pairs it will kill my action (barring an A), and a 3 or a 5 will probably kill it too. What's the best play?