Stage 4 breast cancer

Hello all, I was diagnosed with breast cancer in 2000, had a lumpectomy, 13 lymph nodes removed, 6weeks  radio , then Tamoxifen for 5 years and yearly mammograms for 10 years. There was no spread from the single tumour.. After being unwell for several months I have now been diagnosed with Grade 4 breast cancer with metastasis in my lung and brain, it has come as such a shock after being fine for 15 years. I have had surgery to remove the brain tumour and am taking Letrozole and the hormone treatment seems to be keeping the things under control.My balance is still poor but don't really know how long it takes to recover after brain surgery. Does anyone have any similar experience ?