They say the best revenge is looking good, so take that, Casper Smart!

Jennifer Lopez posted the above photo on Instagram on Monday afternoon and she captioned the sexy snapshot, "She yelled at me "DONT MOVE!" Another shot by Remini... #shemakesmelaugh #notmad #loca #loveher #shesgettinggoodatthis." It's pretty hard to believe that the singer/actress is turning FORTY FIVE on Thursday ... the fact that she looks this good at nearly half a century of age is certainly something to celebrate!

J. Lo and pal Leah Remini have been vacationing in the Hamptons for the last few days, and it looks like they're having a blast relaxing back east. The day before this J. Lo posted a few more poolside pics, and Leah uploaded a video, sharing her exasperation over her BFF's constant hotness.

"Jen asked me to meet up by the pool, right," Leah said while turning the camera from herself to J. Lo. "Here's me - normal, look at this one. Head wrap. Jewelry. Can you be ugly once?! Can you be normal once?! You're such a jerk off!" In case you missed it, click thru to watch...