Katherine Schwarzenegger's handling the news that she has a 10-year-old half-sibling about as well as can be expected.
After Arnold "The Inseminator" Schwarzenegger released a statement admitting he fathered a child with one of his staffers, a heartbreaking betrayal that prompted wife Maria Shriver's decision a week ago to separate, the couple's 21-year-old daughter is tweeting off.
So what did Katherine have to say?
"This is definitely not easy but I appreciate your love and support as i begin to heal and move forward in life.I will always love my family!" tweeted Katherine, the eldest of the couple's four children, who's a junior at the University of California and a newly minted author.
The post came 22 hours after she cryptically retweeted this quote: "worrying is a waste of time. It doesn't change anything. It messes with your mind and steals your happiness."
It sounds like Katherine knew something the news media didn't yesterday.
Meanwhile, E! News has more on Arnold's admission that rocked Hollywood this morning.
A source tells us that while the identity of the "household staff member" remains closely guarded, the mistress is "definitely not a nanny" or someone who took care of the children, the insider reveals that the woman didn't serve as the house manager nor was it Maria's personal assistant.
Meanwhile, despite living apart since he left office earlier this year, the couple have been seeing each other. They jointly attended several family functions since January, even hosting some gatherings at their Brentwood estate, including a dinner party for friends and family on Easter Sunday.
As for when the kids found out about Schwarzenegger's infidelity, a source backs up the version Arnold said in his statement—that he informed Maria and the family in January since his term ran out.
"The kids were totally out of the loop," says the insider. "They did not not know they had a half sibling."