Agree wholeheartedly on the focus of yourself and well being, physical and mental as you come to grips with where you are at. Prior to my BC diagnosis I was in a good place, health and fitness had improved immensely and I had lost 15kgs. What I did come to realise was that state of good place helped me through my BC journey. Now I am on the other side of it and like most, niggling issues as a result of BC and treatment and unexpected surgery for something totally different, I have found that improving my health and well being is the priority and helps me to be me rather than the BC woman.
Yes I lost friends along the way but as they say

Although you maybe feeling as flat as a tack at present if you just take a little step forward then hopefully the one step forward, two steps backwards will subside and it will be steps forward
Take care and best wishes