Suggest Treatment For Depression In A Person With Breast Cancer

Hi, I need your help, my sister, who is 65yo, was just diagnosed w/advanced breast cancer, stage is thought to be either III or my hunch it is IV because she has skin involvement & her breast has completely shrunk (rt side). Her ER & PR are both negative, but her HER2 is positive. No tx has been done yet, she is going to have a Pet CT this week, along with breast MRI to find out if she has distant metastasis. I believe she has skin involvement plus LAD. I would appreciate your opinion. This was accidently discovered when she was recently admitted to ER for a cerebral stroke. Her head CT did not 100% reveal Metastasis due to the edema & blood resulting from her stroke! Quit smoking 2 yrs ago, menopausal, delivered 3 healthy kids & breast fed them, she is overweight now, due to loneliness & depression, eats a lot sweets, but otherwise in general good health. I hope these details help. Please advise. Thank you.