Clea Shearer has recently revealed that she has breast cancer, sharing that she is set to undergo a double mastectomy.

The 40-year-old was in New York City to film a segment for the Today show with co-star Joanna Teplin when she found two small lumps in her right breast during a self-exam.

Within a few weeks, Shearer learned that she had stage 1 invasive mammary carcinoma – an aggressive form of breast cancer.

The star of Get Organized with the Home Edit told PEOPLE, “I felt something, a mass, a lump. But I didn’t know what a lump actually even felt like, so I was just in my hotel room Googling, ‘What does a breast tumor feel like?’”

After finding the lump, she called her OB/GYN immediately but was told the soonest appointment was in May. She saw her primary care physician, who was able to order her a test within a few days.

She said, “I went in for a mammogram and then it turned into an ultrasound and the ultrasound came back as ‘suspicious and concerning,’ which led to an emergency triple biopsy, that same day. The radiologist at that point, pretty much confirmed that she would be shocked if this was anything but cancer, but we waited for the pathology to come back from the biopsy.”

On March 11, Shearer got the news about her diagnosis.

She said, “I think I had convinced myself, because of my age and because I don’t have a history of breast cancer in my family, that it was something, but it would not be a cancerous tumor.”

“It’s crazy to look in the mirror and tell yourself that right now, as you’re physically standing there, you are a person who has cancer,” she continued. “It’s crazy to say it out loud. It was really scary and really, really, really emotional. At that point, I didn’t know what stage it was. I didn’t know if it had spread. You go into a pretty dark place until you have more information.”

She told PEOPLE that she is set to undergo a double mastectomy surgery today, after which it will be determined whether she will need chemotherapy or other treatments.

Shearer turned to her close friend and breast cancer survivor, Christina Applegate. She said, “[Christina] was my first phone call and my second and the last few, too.” Applegate was diagnosed with breast cancer in 2008 and underwent a double mastectomy, She also had her ovaries and fallopian tubes removed.