Having lost my wife Therese eight years ago to a very aggressive brain tumor (stage 4 glioblastoma) I completely understand what you are going through. The nine months between the time she was diagnosed until her passing were life altering to me and it wasn't until it was all over that I had time to reflect on the entire experience. You discover that you were able to do things during that ordeal that you never thought would be possible. While a trying time of your life, with the help of family and friends you will move on - although that might be hard to accept at the moment. Life really does go on my friend.
My condolences for your loss Dave. I have had some close relatives pass away from cancer and it is terrible. I hope you find peace in the days to come.