Constance Zimmer is going public with the secret breast cancer battle she faced earlier this year.

“October is #breastcancerawarenessmonth and I never thought I’d be honoring it with my own story,” the actress began in an emotional Instagram post Sunday.

“On March 13th when I was away from home – I heard these words from my doctor over Zoom: ‘You have DCIS, also refereed to as Stage 0 breast cancer,’” she recalled. “The silence was deafening.”

The “Entourage” alum told her followers her cancer journey is the “biggest secret [she’s] ever held.”

She only confided her health struggles in those close to her, including daughter Colette and husband Russ Lamoureux, who was the first call she made post-diagnosis.

“The mental toll that followed was overwhelming … as I began talking to many more doctors then I would’ve liked,” Zimmer, 55, continued, noting that she felt “like [her] options were limited.”

She explained, “Most suggested what was the quickest way to get this mass out ASAP, which was a mastectomy.”

At the time, however, she questioned whether that was the route she wanted to pursue.

“What if that’s not what I want?” she asked herself. “What if I want to save my boob instead?”

After consulting with a doctor, Zimmer decided on a lumpectomy, a breast-conserving surgery that removes a tumor and a small rim of healthy tissue around it while keeping most of the breast intact.

“It did take three surgeries — three weeks in a row, but [my doctor] did it, she saved my breast and it looks good too!” Zimmer gushed.

Zimmer, who starred as Ann Marie Messina, the mother of Carolyn Bessette, in FX’s “Love Story” earlier this year, shared that she was going through her health woes while promoting the popular series.

“During all of this I was out on a very public press tour for ‘Love Story,’ while keeping my diagnosis and treatment private,” she explained. “I then followed my surgeries with radiation, while celebrating my Emmy nomination.”

Zimmer clarified that she is now cancer free and encouraged other women “to please not wait until you have symptoms to get yourself checked in all ways possible.”

She is now “celebrating what [her] body got [her] through over the last seven months: pure shock and fear alongside pure joy and gratitude.”

Zimmer concluded, “From hospital gowns to Emmy glamour, this was one hell of a ride.”