"We split up ages ago. We have been not together far longer than we were ever together. But I really love him and like him and we make each other roar with laughter," Beckinsale explained of her close relationship Sheen, which she admits is confusing for some.
The two met in 1995 and split in 2003, though share 17-year-old daughter Lily, who remains both of the actors' main priority.
"I really love [Sheen's] girlfriend [Silverman] as well and we are lucky we both get on, and Lily gets on great with her," she revealed. "Having as many strong females in your teenage daughter’s life as possible is a good thing."
Lily's definitely got a lot of strong females in her life, but she's also surrounded by a lot of performers -- which is why Beckinsale wouldn't be surprised if her daughter decided to become an actor.
"That would be like sitting there with a glass of wine and saying you can't have a drink. I can see why she wants to do it," she explained. "I don't love the downside of it for my baby. But it's not like she hasn't seen her parents having a real experience of what it's like."
ET recently sat down with Beckinsale -- who split from her husband, Len Wiseman, in October -- where she spoke more about navigating the holidays with Lily, Sheen and Silverman.
"We had Thanksgiving at his girlfriend's house and they're having Christmas at our house," she said. "We like hanging out with each other, so it's not like, 'Oh, who gets Lily?' or whatever. It's like, 'Whose house are we going to be at?'"
"I think we both really felt like, we really agreed on what would be the right thing for Lily," she added of how they're able to get along so well. "And I think, you know, not hating each other and fighting and all that would be awful for her. I think we've also got a really similar sense of humor, and I do find that humor can save an awful lot of things and help a lot of things."