From PEOPLE Magazine Click to enlarge
In the world of professional ballroom dancing, a dazzling smile is as important as fancy footwork. But for Karina Smirnoff, putting on a happy face has become more complicated than any paso doble. "I'm definitely heartbroken," says Smirnoff, a regular dancer on the ABC reality hit Dancing with the Stars. Her breakup in June from actor Mario Lopez, with whom she was paired in 2006 on the third season of the show, left her wishing she could "just crawl into bed, eat ice cream ... and not come out for weeks."

Though it was only ever tacitly admitted, Smirnoff and Lopez had a two-year relationship, which ignited the moment they met. "I thought that he was extremely hot and charming," she says. "We actually tried to fight the attraction as long as we could. But obviously, that didn't last too long at all."

Indeed, six months after they started dating, Smirnoff, 30, moved into Lopez's Los Angeles home, with the Ukranian-born beauty firmly believing that she had won the ultimate prize. "We were always laughing, joking, having a good time," Smirnoff says. Love-struck, she shrugged off warnings about her new beau's somewhat checkered relationship résumé (Lopez's marriage to model Ali Landry ended after only seven weeks). "People were saying things," she says, "and trying to bring his past into our present. I just thought that I would much rather trust him than everyone else."

Though Smirnoff admits the relationship was always stormy—"The passion was through the roof!" she says—the couple hit a particularly rough patch when Lopez, 34, headed to New York to appear on Broadway in A Chorus Line, while Smirnoff stayed in Los Angeles on DWTS. "When people say, 'Absence makes the heart grow fonder,'" Smirnoff says, misty-eyed, "I don't think it's true."

Soon there was gossip, followed by reports from women who claimed to have led Lopez astray. Smirnoff became a target of the rumor mill as well, romantically linked to her new dance partner, R&B singer Mario, as well as E! correspondent Michael Yo, both of whom Smirnoff insists were merely "good friends."

Finally, with tension between Lopez and Smirnoff building, Smirnoff says she confronted her boyfriend about his reported infidelity over the phone. "He pretty much confirmed everything," she says. "It felt like the world came to an end for a second. I hit the ground, and I couldn't get up. That was when all the little pieces came together in my head. You come to that realization that this is not what you want out of love and out of life, and this is not who you want to be with."

Asked for a comment, Lopez says simply, "Karina is a phenomenal and talented woman. And I have the utmost respect for her."

Now Smirnoff, the five-time U.S. National Champion in Latin Ballroom Dance, is keeping busy until the next season of DWTS by focusing on a workout DVD and lifestyle book while creating a dance-related charity to help at-risk youth. "I work until my head hits the pillow, so I don't have any free time to think about it," she says. As for dating again, she plans to take it one step at a time. "All women are attracted to the bad boys," she says, "[but] when you're looking for the ideal man, it's how he treats you that is most important."

Wiping away a tear, she flashes a smile that, while not competition-ready, is still hopeful. "Everything happens for a reason," she says. "It's hard, but time heals everything."