@Simo Sorry to hear that you have been through so much tragedy in your life. I imagine this has taken a huge toll on you & then discovering that you now have cancer, has completely shattered you. You're not being negative but are just showing a natural response to how scared you are & how this discovery is something you think is quite insurmountable.
Many of us here, me included, have lost loved ones through this disease so we can relate to your fear. I lost my mum when I was 4 y.o. to ovarian cancer so following my BC surgery & rad treatment, i chose to have my ovaries removed so it would remove the chance of me getting a secondary cancer there. I remember lying on the operating table with tears in my eyes saying to the surgeon that i was doing this for my mum!
Sometimes, information gives you power & an understanding of how to move forward. You could use your family history as a way to learn about what may be best for you in regard to treatment & future planning. Have you discussed with your medical team about getting a genetic test done. if you have had many in your family succumb to cancer, you may be eligible to have a free test. There are lots to consider if you go ahead, but it could change the direction of your treatment plan depending on the outcome & it would also be information for your children in the future. I had the test & it came back negative so i went ahead with my treatment plan.
I know you have said you tried counseling but have you tried seeing a clinical psychologist who specializes in cancer patients. I have heard them speak at conferences & they are amazing. You could ask a breast care nurse, someone from your medical team or hospital staff, if they know of anybody suitable.
i will be thinking of you this week & wishing you love & strength as you prepare for your operation. Go for long walks, take in the sunrise/sunset & deep breaths. xx.