J Lo and Diddy: Still Sweet for Each Other at AMA After-Party

Jennifer Lopez and Diddy flashed back to the turn of the Millennium -- when he was Puff Daddy and she was not Jenny From the Block yet -- and partied after the AMAs as if they were still dating.

Clearly there are no hard feelings between the exes who looked like they had a blast at J Lo's after-party. They've come a long way since ending their relationship 16 years ago ... when Diddy got booked for a weapons violation after that NYC nightclub shooting.

Good to see they've put it all behind them. Jennifer's current guy, Casper Smart, was there too ... we got all 3 outside the party.