Mariah Carey was "totally blindsided" by the way her breakup from her ex-fiance, James Packer, publicly unfolded, especially given how in love the two seemed to be in the weeks leading up to their split.
In August, the two appeared happy and very much smitten with one another, with the billionaire sending love notes to Carey. A source tells ET the 49-year-old businessman would send emails to Carey expressing his love for her, in which he referred to her as "MCP," for Mariah Carey Packer.
"I'm in love with you and can't wait to get married and be together forever," one note from August reads.
WATCH: EXCLUSIVE: Mariah Carey Plans to Keep Her $10 Million Engagement Ring After Being 'Blindsided' by James Packer Split
In another email that month, Packer wrote to 46-year-old Carey that she had "all [his] love, laughter, light, respect and appreciation and admiration," and called her his "soulmate." "I miss u my girl and love you so much," he wrote.
The affectionate emails continued in September, when for Packer's 49th birthday on Sept. 8, Carey gifted him with a Cartier wedding band, the source reveals.
"I loved my birthday present," Packer wrote to Carey as well as her manager, Stella Bulochnikov.
According to our source, the two had planned to marry in the new year and went to Greece on Sept. 13 to specifically discuss wedding plans, after the singer's divorce from her ex, Nick Cannon, was finalized just days before the trip. On Sept. 22, Carey Instagrammed a snap of her and Packer smiling in Mykonos.
Of course, the trip didn't go as planned, and Carey's rep confirmed to ET exclusively last month that the two got into a fight during their vacation in Greece, and haven't spoken since.
Despite the fight in Greece, Carey still Instagrammed a happy pic of the two on Sept. 26 -- a month before news of the breakup broke on Oct. 27 -- in which the two adoringly gaze at one another.
"Mariah was actually blindsided when news broke of her split with James as her intention was always to release a joint statement and maintain an amicable relationship with her now ex," our source says.
"They were so happy," the source adds about their relationship. "Mariah was a source of love for James."
Now, the two are currently in discussion, and Carey is planning to keep her 35-carat, $10 million ring from Packer, the source says. The source also reveals that Packer and Carey are "discussing the house" in Calabasas, California. After Packer asked her to leave the rental home, Carey was initially forced to live at the Beverly Hills Hotel for a couple of weeks. This was "completely out of character" for Packer, the source adds.
Carey hasn't been keeping a low profile since the split, hitting the town in Los Angeles in sexy outfits. Although Carey was most recently spotted wearing her engagement bling on Sunday when she took her twins -- 5-year-old Monroe and Moroccan -- to Jessica Biel's kid-friendly restaurant, Au Fudge, just one night earlier, she wasn't wearing the ring while enjoying a dinner with pals at celeb hot spot Catch LA.
WATCH: Mariah Carey Rocks Fishnets, No Engagement Ring During Night Out With Backup Dancer
"Mariah is traumatized by all of this but is putting on a brave face," another source told ET on Monday. "She never meant to fall for James."
Watch the video below for more on Packer and Carey's negotiations.