I would have had to fold too, but that would have been hard to do with that much in the pot. :S I don't think he had the straight. You raised, then he reraised and he called your reraise...so I'm thinking he had decent pockets, but was scared by your reraise and he should have known you had pockets. Therefore, he could have hit a set on the flop. He may have also been dumb and called your reraise with AK and then thought you had queens, so he all inned to keep you from chasing. I doubt he thinks you are on a flush draw, so if he is trying to push you out he probably thinks you're on the straight draw and hes got a set. If you've been playing tight he may also just know he can scare you away too. :P