Olivia Munn is opening up about her harrowing health journey. 

Just over a month after the 43-year-old shared she'd been diagnosed with breast cancer a year earlier, Olivia is recounting that time in her life, including her fears and the medical processes she underwent.

"I was not someone who obsessed over death or was afraid of it in any way," Olivia—who shares 2-year-old son Malcolm with boyfriend John Mulaney—told People in an interview published April 17 of receiving her diagnosis. "[But] having a little baby at home made everything much more terrifying. You realize cancer doesn't care who you are; it doesn't care if you have a baby or if you don't have time. It comes at you, and you have no choice but to face it head-on."

In this case, the Newsroom actress had to square up against bilateral breast cancer, specifically, a fast-moving and aggressive cancer called luminal B. Within 30 days of her diagnosis, Olivia underwent a lymph node dissection, a nipple delay procedure—a surgical process which preserves the nipples ahead of breast reconstruction—and a double mastectomy.

"I had amazing doctors, but it was still a negotiation sometimes on what we are doing," she remembered of deciding whether to undergo the nipple delay. "But I'm glad I did. I want to give myself the best shot of keeping the parts of me that I can keep."

And even though she knew the double mastectomy was recommended by her doctors as a way to remove all the known cancer—as well as reduce any further reduce to her—Olivia still struggled with the reality of the procedure. 

"There's so much information, and you're making these huge decisions for the rest of your life," the Daily Show alum explained. "I really tried to be prepared, but the truth is that nothing could prepare me for what I would feel like, what it would look like and how I would handle it emotionally. It was a lot tougher than I expected."

The diagnosis was all the more shocking for Olivia as she'd tested negative for the BRCA gene and received a clean mammogram result just three months prior.

"I was walking around thinking that I had no breast cancer," she recalled. "I did all the tests that I knew about."

She credits her OB-GYN, Dr. Thaïs Aliabadi, with catching her cancer after she recommended Olivia calculate her lifetime breast cancer risk score using the Tyrer-Cuzick risk assessment calculator, which is available for free online. Scores of 20 percent or higher are considered high risk: Olivia received a 37.3. A subsequent MRI ordered by Dr. Aliabadi is how they discovered the cancer. 

Giving herself time to recover from her double mastectomy earlier last year, Olivia didn't undergo reconstruction surgery until last fall. During this time, she kept her diagnosis secret from the public. Looking back, Olivia noted of the decision, "Keeping it private for as long as I did allowed me time to fight without any outside noise at all."

Olivia's care has so far not required radiation or chemotherapy, but in November the Predator actress began taking a hormone suppression therapy to limit her future risk. The treatment has put her into medically induced menopause, or as she explained, "I'm constantly thinking it's hot, my hair is thinning, and I'm tired a lot."

Through it all, however, Olivia has had two important people by her side: John and Malcolm. And it was the comedian's support that helped guide her through the difficult moments balancing her treatment and life with a little one.

"It would've felt like climbing an iceberg without him," Olivia gushed of her partner of three years. "I don't think he had a moment to himself, between being an incredibly hands-on father and going to and from the hospital—taking Malcolm to the park, putting him to nap, driving to Cedars-Sinai, hanging out with me, going home, putting Malcolm to bed, coming back to me. And he did it all happily."

And above all, she's grateful for the time she's been given with Malcolm. 

"When I'm with him," Olivia said, "it's the only time my brain doesn't think about being sick. I'm just so happy with him. And it puts a lot of stuff into perspective. Because if my body changes, I'm still his mom. If I have hot flashes, I'm still his mom. If I lose my hair, I'm still his mom. That's really what matters the most to me. I get to be here for him."