The 36 year-old actress reveals the hardest decision she's had to make.

Today, Christina Applegate spoke to Robin Roberts on Good Morning America about her breast cancer diagnosis, and the personal decision she had to make. Christina says when she discovered she had cancer, she was "pissed off and mad," then went right into business mode. After researching her treatment options, she opted for a double mastectomy to ensure the cancer wouldn't return.

Since her mother had endured cancer twice, Christina looked to her for strength. "It must have been difficult for her to know she gave birth to a daughter with this gene, but she is a quiet warrior for me," she said.

Now free and clear of cancer, Christina credits an MRI with saving her life. "It's a very expensive procedure, but everyone should have this testing," she said. "My goal is to raise money for women to have MRI and gene testing. It's the most effective way to save lives."

She plans to have reconstructive surgery over the next few months, and is looking forward to her future. "I'm not going to die from breast cancer," she said. "But when I'm old, I will have the cutest boobs at the nursing home."

Watch the video to hear her story: