Mima, all of the feelings you have described are totally "normal" for what is an abnormal situation - bc diagnosis.
All the ladies here on the forum can totally relate to being confused, having head spins, tears, frustration, sleepless nights - all of these and more.
I am sure that until your diagnosis you had perhaps felt well and so a diagnosis that you have breast cancer is completely shocking and overwhelming. In some respects, a lumpectomy and radiotherapy is something that is not as invasive as a mastectomy and chemotherapy but regardless this is happening to your body and I am sure you feel as though your body has let you down.
Like @Nadi I am the mother of boys and Mum's seem to be the glue that holds a family together. Not only do you feel helpless that you can't fix it for yourself, you also can't fix it for your family.
No need to feel guilty and perfectly ok and normal to feel scared and frightened.
Knowledge is everything - ask lots of questions, take a relative or friend to appointments, your BCNA kit should be really helpful and most of all there is the online forum here.
Best wishes to you.