Olivia Munn is opening up about a health battle.

The Newsroom star shared she has been diagnosed with breast cancer, noting that the diagnosis came two months after she took a genetic test that had negative results.

"In the past ten months, I've had four surgeries," she wrote in a March 13 Instagram post, "so many days spent in bed I can't even count and learned more about cancer, cancer treatment and hormones than I could ever have imagined. Surprisingly, I only cried twice. I guess I haven't felt like there was time to cry. My focus narrowed and I tabled any emotions that I felt would interfere with my ability to stay clearheaded."

As the actress, who shares 2-year-old son Malcolm with John Mulaney, went on to explain, "I've tended to let people see me when I have energy when I can get dressed and get out of the house, when I can take my baby boy to the park. I've kept the diagnosis and the worry and the recovery and the pain medicine and the paper gowns private."

"I needed to catch my breath," she continued, "and get through some of the hardest parts before sharing."

The 43-year-old went on to share that she underwent a double mastectomy and credited her doctor with saving her life.

"I'm lucky," she noted. "We caught it with enough time that I had options. I want the same for any woman who might have to face this one day."

And as Olivia explained, she's grateful to have had loved ones by her side throughout this journey.

"I'm so thankful for my friends and family for loving me through this," she continued. "I'm so thankful to John for the nights he spent researching what every operation and medication meant and what side effects and recovery I could expect. For being there before I went into each surgery and being there when I woke up, always placing framed photos of little boy Malcolm so it would be the first thing I saw when I opened my eyes."

The Six star also shared gratitude for those who have been on a similar path and have helped her through this process.

"Thank you to the friends who've had breast cancer," she wrote, "and the friends who connected me to friends who've had breast cancer for guiding me through some of my most uncertain and overwhelming moments."

Shortly after detailing her journey, Olivia received an outpouring of support from friends, colleagues and celebs sending their well wishes. Her boyfriend John also wrote a touching message on behalf of himself and their baby boy, commenting, "Thank you for fighting so hard to be here for us. Malc and I adore you."

Additionally, Lindsey Vonn noted, "You are brave and strong and I'm thankful you are ok. Sending all the love." Added actress Kristin Davis, "Your experience is so powerful to share! Sending you so much love and strength, so grateful you found out early and can only imagine the emotional roller coaster you have been on."

Keep reading for more moving messages of support.

After Olivia Munn shared her breast cancer diagnosis on Instagram March 13, she received a flood of well-wishes from fans, friends and fellow stars.

"Thank you for fighting so hard to be here for us," the comedian wrote to his partner. "Malc and I adore you."

"Thank you for sharing this!" the Big Bang Theory actress commented on Instagram. "Wow."

"You are so strong Olivia!" the Fellow Travelers star wrote. "Grateful you found this early. Sending you love always."

"Sending you and your family love & healing vibes," the Modern Family alum commented. "You are so strong."

"I love you friend," the Emmy winner told her pal. "May God continue to bless you with good health and a long happy life."

"Your experience is so powerful to share!" the Sex and the City actress commented. "Sending you so much love and strength , so grateful you found out early and can only imagine the emotional roller coaster you have been on."

The Office alum commented, "I love you."

"You are brave and strong and I’m thankful you are ok," the Olympic athlete wrote. "Sending all the love."

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