Long before Busy Philipps and Michelle Williams were hitting red carpets as everyone’s favorite Hollywood bestie duo, there was Paris Hilton and Nicole Richie — the lovably mischievous twosome that captivated the world with their wild, double trouble antics, both on-screen and off. Now, they’re giving us serious pangs of nostalgia, as Hilton has just posted a birthday tribute to her former frenemy that has our hearts singing with pure joy.

For three glorious seasons, we watched as the two women starred side by side in The Simple Life on FOX, a Green Acres-inspired comedy in which they lived with a family on a farm, took a road trip in a (what else?!) pink pickup, and endured various internships as the best of friends.

A personal falling out between the two in 2005 didn’t stop the show, with the ladies going on to film two more seasons together for E!, but it DID seem to put a screeching halt on their RL friendship. Neither star ever officially confirmed what caused the rift, though Hilton did release a cryptic statement at the time which read, “It’s no big secret that Nicole and I are no longer friends. Nicole knows what she did, and that’s all I’m ever going to say about it.”

Remaining true to her word, the twosome that was once so inseparable seemed to go their separate ways. Richie went on to design a best-selling fashion line, House of Harlow, write two fictional novels, score several more TV shows (Candidly Nicole, Great News) and marry rocker Joel Madden of Good Charlotte, with whom she had two kids, while Hilton spawned her own business empire that now consists of 24 perfumes, regular gigs as a DJ, club and movie appearances, and more.

Just when we’d all but given up hope for any type of real rekindled friendship, however, Hilton took to Instagram with a post to commemorate the birth of her former bestie/frenemy that not only did just that; it practically made us weep. “Happy birthday @nicolerichie,” she wrote on a gallery of no less than 10 snaps from the pair’s brighter days. “Looking through all these photos brings back so many special and amazing memories. Just wanted to let you know that I am so happy for and proud of you. Such a beautiful family you have created and loving your new show @NBCGreatNews, so hilarious!”

As if that wasn’t enough to warm our hearts, the socialite added one final line that had us feeling all the feels. “I will always think of you as a sister and think of you often. Love and miss you. #SanaSa #BillandSill.” Oh. Em. Gee! Our hearts can hardly stand it!

Between this and Hilton’s recent reconciliation with her former assistant Kim Kardashian West (who Richie may or may not have once stolen lipstick with), it sounds like the gang’s ready for a reunion, and we are SO here for it.

Happy Belated Birthday, Nicole!

Have you ever reached out to a former bestie? What happened? Tell us @BritandCo.

(Photos via Peter Kramer + Kevin Winter/Getty)