Well i think you played that hand way toooo tight man.
I mean, let's see what reasonable hands he could have, that will beat your Aces? He called a raise without position, so probably we can exclude TT,99. If he isn't a totally rock or call station, he would re-raise you with such hands. Probably 33 could get lucky, then we are likely beat, but we have still outs for nut-flush, to not forget! Also it's less likely that he flopped flush, because we have a diamond on a hand. And it just happens too rarely to flop a flush at all. So which hands could it be? I would say it could be some high cards hand like JT+ with one diamond card, although JT would likely play that way also without diamond, because of straight outs. Also it could be a lot of hands that hit top pair with Ten and try to defend their hand. It could be 9T or JQ too, but along with 33 thats the only hands i can imagine he could have and we are standing sucks against. But then again, nut-flush outs are still there, you know.
Considering all that, AA in a huge part of possible situations is an absolute favorite and in just a few underdog. So it's a must call on turn to me.