I think you have to call the river. Given that you've described him as 'bad loose and agressive' it could easily be the case that he's gotten excited over a real hand that hit, like AK-AJ. Alternately, he be trying to scare you off with the flush showing up. If he's a bad LAG, then there are too many hands he could play this way to lay this down.

My big worries are 88 and a bigger flush.