It's over!

Jon Hamm, 44, and frequent co-star Jennifer Westfeldt, 45, have ended their almost two-decade-long relationship, months after his rep shot down a breakup report, E! News confirmed on Monday.

"With great sadness, we have decided to separate, after 18 years of love and shared history," the former couple said in a statement to People magazine. "We will continue to be supportive of each other in every way possible moving forward."

The Mad Men alum and the actress, director and writer began dating in 1997 and were last photographed in public at the New York premiere after party for his latest acting project, the Netflix series Wet Hot American Summer: First Day of Camp, on July 22 (pictured below).