Christina and Jordan, who have a son Max Liron Bratman together, split in October before the singer began dating Matt in November.
Coincidently Christina and Jordan's five-year marriage officially ended exactly three years ago when their divorce was finalised on Valentine's Day in 2011.
Over the past three years Matt has become close to Christina's six-year-old Max and the trio live together in LA.
"He's the love of my life, and I adore him," Christina said of her son shortly after splitting from Jordan. "He's such a character, and he's so happy and at the end of the day, that's what's most important."