@robynwithay, I don't have metastatic breast cancer, but I have had metastatic lung cancer for the past 5 years, and breast cancer stage 1B within this past year. I did really struggle with the metastatic diagnosis for the first few years. I was in a fog and just kept living my life as I had prior to cancer. It's a difficult diagnosis to process, and asking for help from your oncology office (social worker or therapist who is good at working with cancer patients) may help to restore some joy and purpose to your own life. Having an adult son that needs you for his care adds an additional weight to your shoulders. You have a lot to process and work through. I hope you are able to find some help. You shouldn't have to do this on your own.
Have you learned anything more from the recent PET scan?