03/06/2008 at 06:00 AM EST
She may have written a tell-all book, but Valeire Bertinelli was suddenly very tight-lipped Wednesday night when asked about ex-husband Eddie Van Halen's mystery illness
"I really don't think it's anybody's business," the Jenny Craig spokeswoman, 47, told PEOPLE at a Cincinnati book-signing for her new memoir, Losing It: And Gaining My Life Back One Pound at a Time
. "He's being proactive and that's good."
The 53-year-old Van Halen guitarist "is undergoing a battery of comprehensive medical tests," the band announced on its Web site
Monday. (The rocker, who has a long history of drug and alcohol abuse, previously battled cancer. In 2002, he announced he'd beaten the disease
.) As a result of the star's undisclosed illness, they cancelled four concerts, including one slated for Wednesday in Cincinnati.
In fact, Bertinelli said she's just as disappointed as other Van Halen fans. "We scheduled the signing early so we could make the concert in time," she said. (Her teenage son, Wolfie, is touring with dad as the band's bassist.)
Instead, as the signing at Joseph-Beth Booksellers wound down, the former child-star and her longtime boyfriend Tom Vitale headed out in search of seafood and champagne.
They certainly had plenty to celebrate. Bertinelli had just gotten a call announcing that Losing It
had made it onto the New York Times
Bestseller List. (The actual list is not published until Sunday.) Upon hearing the news, the ecstatic actress screamed, "Holy crap!"
Reporting by ANGELA T. KOENIG