Maria Shriver and her children are working to "rebuild our lives and heal"
in the wake of discovering that Arnold Schwarzenegger fathered a child
with another woman.
One of the ways Shriver, 55, will seek solace for her family and
herself during the painful breakup
of her 25-year marriage, friends say, is through prayer.
"She will spend a lot of time on prayer and recovery,” a friend tells PEOPLE in its cover story
As for whether Shriver knew of her husband's infidelity or that he had fathered another child, close sources believe the answer is clear.
"I guarantee she had no idea," the same friend says. "Knowing Maria, there is no way she would have stayed in that house."
Asked how Shriver is feeling, the friend adds, "More than anything else and knowing Maria, I imagine she is just terribly sad right now.”
Despite the pain she's in, Shriver has made sure to keep up prior commitments. She put on a brave face
while attending a taping of pal Oprah Winfrey
's show in Chicago on Tuesday.
"You've given me love, support, wisdom," Shriver said before introducing a segment about her friend's love of education. "And most of all, the truth."
For much more on Maria Shriver and Arnold Schwarzenegger’s split – including how Shriver was blindsided by the news of her husband's infidelity – pick up the new issue of PEOPLE, on newsstands Friday