Garth, who starred alongside Amanda Bynes on the sitcom "What I Like About You" from 2002-2006, has not spoken to Bynes since the young actress' legal woes began mounting this year.
"I'll always have a special place for her in my heart," said Garth. "You can't play sisters with somebody for four years and not love them and take them under your wing."
Garth and her husband, actor Peter Facinelli, split earlier this year after 11 years of marriage. Facinelli is now romantically linked to actress Jaimie Alexander, his co-star on Showtime's "Nurse Jackie." Garth and Facinelli share joint custody of their three daughters -- Luca, 15, Lola, 10, and Fiona, 6 -- whom they remain utterly devoted to.
"I have the girls for Christmas Day, and we're gonna have a traditional Christmas," said Garth, "then we're traveling to see some friends in Virginia and then their dad's going to be taking them for a few days to go skiing or something. It's all new, this splitting of the holidays. It's definitely new. Definitely new and foreign; but I'm jumping in with both feet, and I'm going to make it the best holiday for my girls that I possibly can."
For all the "Twilight" fans wondering whether Garth has seen Facinelli's latest movie, "Breaking Dawn - Part 2":
"I haven't," she said. "My girls are all fans, and I support them loving it and loving the movie that their dad's in but, no, I haven't seen the new one."
Garth also admitted she hates being back on the dating scene.
"Who wants to date?" she said. "It's awful, and then add to it being photographed while doing it, and the scrutiny that that entails. It's impossible."
Garth also took the opportunity to clear up rumors that she likes mean guys.
"It went viral that I like bad boys, like mean people. No, I'm a little edgy so I like someone who has that edge. You can have that edge, and you might not notice it by looking at someone, but it's in there ... I'm into nice guys!"
Garth told CNN that she doesn't have a "type," per se.
"It's all about an energy," she said. "If there's an energy between two people it doesn't matter what you look like or what you do for a living or where you live."
As the interview wrapped, Garth said she was heading straight to the airport.
"I'm gonna get a piece of pizza in the car on the way to the airport, maybe some crazy (street vendor) nuts. Hold the maggots."