Got my results and I’m terrified

This is what it says. I have a 16 month old and 11 year old and all I can think of is the worst. Anyone have something similar ease my thoughts. So far based of mammogram and ultrasound no signs in lymph nodes but I know that can change with mri. I am already thinking a double mastectomy just so it’s all gone and ease my stress I know I’m jumping ahead here. Also any suggestions on how to talk to my tween? We have always been open and honest with each other but I’m thinking I not say anything to her until a plan is in place as well.

Left breast, .9cm mass, 2:00, 4 cm from nipple, ultrasound-guided core needle biopsy: -INVASIVE DUCTAL CARCINOMA, GRADE 2. -ASSOCIATED DUCTAL CARCINOMA IN SITU, NUCLEAR GRADE 2, SOLID PATTERN.

  -Immunohistochemical stains:
       -Estrogen receptor: Positive (strong intensity in 95% of tumor cell nuclei).
          (Intensity score: 3/3; Proportion score: 5/5; Total Allred score: 8/8).
       -Progesterone receptor: Positive (strong intensity in 95% of tumor cell nuclei).
          (Intensity score: 3/3; Proportion score: 5/5; Total Allred score: 8/8).
       -Ki-67 proliferative rate: 20%.
       -HER-2: negative (0).
       -E-Cadherin: Positive.
       -SMM, p63: Performed.