Emma Stone's life came into "sharp focus" when her mother Krista was diagnosed with cancer in 2008.The 24-year-old actress has revealed how finding out her mother had triple negative breast cancer, an aggressive form of the disease, made her want to "stop making movies" because she was so terrified, but adds the experience has made her value the time she gets to spend with her family more.She said: "It was terrifying. Your life comes into sharp focus."The 'Zombieland' beauty added watching her mother's ordeal "gave me a greater appreciation for her, and all she's capable of."Krista - who attended the Triple Negative Breast Cancer Foundation's Peace, Love and Cure fundraiser in New Jersey, US on May 21 with Emma and her boyfriend Andrew Garfield - has more surgery ahead of her but has been free of cancer for more than four years and credits her famous daughter for helping her get through everything.She told People magazine: "I was convinced I would die. I'm sure, in private Em, lived in fear, but she stepped up."