VERY newly diagnosed Mucinous breast cancer

Hi @Taji I can't offer any help with that particular type of bc but I know the diagnosis would have been a shock.  I was diagnosed in December and have since had surgery and now on chemo.  My best advice is to try to take it one step at a time and stay away as much as possible from Dr Google - at least the general info on there.  You don't say what discipline you retired from but I suspect you're probably someone who likes to research to plan your course.  Your surgeon and team will advise you about your course of action but you probably won't find out exactly what your cancer is until you have surgery.  In my experience, it's only then that they can see the exact dimensions of the tumour, node involvement and hormone receptor type.  
On another note, welcome to this group.  You will find it a great way to connect with others who understand what you're going through and a source of information, advice and support (with a few laughs along the way).
Good luck with the next steps.