"He called me on Christmas Day and told me he's engaged," his grandmother, Sadie Bomar, kvells to Gossip Cop. "The family loves Jessie. ... She's a very sweet girl."
Grandma, who was apparently sworn to secrecy until after the holidays, also chatted up Radar Online about the question-popping, which, depending on which source you believe, either took place in the mountains of Jackson, Wyo., (per Us), or in Montana (per Grams and People).
Justin reportedly presented Jessica with a "custom-designed" ring.
Sadie describes the actress as "upright" (presumably in moral fiber, not posture), and bubbled that she'll be "a lovely member of the family."
"She's a wonderful campaigner for the environment and Justin is, too -- a fine young man," she gushes. "They don't know if the wedding will be in Memphis or Colorado. It's all very new. They haven't made any plans yet. Justin, his mom and dad and Jessica have all been in Montana all Christmas and New Year, that's when he proposed."
As for the nuptials, "You know Justin, he's very laid back," says his grandma. "He was excited, but he don't make a big episode out of anything. It just seemed like the right time for him, I guess."