Denise Richards: “I Can’t Believe How Fast Five Years Have Gone”

Denise Richards is preparing to send daughter Sam, 5, off to kindergarten this fall. How is she feeling about this new stage in her child’s life? “It’s complicated,” she told PEOPLE Saturday at the Much Love Animal Rescue’s 3rd annual Bow Wow WOW Howlywood fundraiser in Los Angeles.

“It’s bittersweet,” says the actress and reality TV star. “Sami starts kindergarten, which I cannot believe, in a couple of weeks. I’m so sad about it.”

“I can’t believe how fast five years have gone,” says the mom of two. “I’m very proud of her and very happy, but from here on out she’s in school.”

Denise and ex-husband Charlie Sheen are also parents to 4-year-old daughter, Lola Rose.

The 38-year-old supports the Much Love charity’s mission and also has rescue dogs at home with her. She says she can’t help but open her home to animals in need: “I’ve always been that way. Ever since I was little I always brought home every little stray dog who didn’t have a home. My daughters love animals as well, so I can’t help it.”

Denise’s It’s Complicated reality show on E! has recently completed it’s second season.