Feeling very stressed and worried

Hello everyone, I have just been diagnosed with DCIS in three areas of one breast.  I feel sick to the stomach and extremely worried.  Have an appointment with surgeon on 8/4 to discuss mastectomy and breast reconstruction.  Don't really know much at all other than what I have been reading.  Trying extremely hard not to think about things but you know how it is, your mind wonders and thinks about the future and what is to come. Any help will be extremely appreciated.   :(