Tina,
I am sorry for where everything is right now with your mother. I am sure when you sought out a second opinion, this is not what was expected. But try to remember that you went because you wanted to know, not because you wanted to be told something different. Now you are armed with the correct assessment. It sounds like the first diagnosis did not accurately stage the cancer and going from a Stage II to a Stage IV gives the medical team a much clear picture of what they are dealing with and how to formulate the best possible treatment plan to battle this disease. You wanted another opinion because you were not comfortable with the first. I just wish the outcome could have been different but there will be a more precise plan from the information obtained during the surgery. Does this even make sense?
Your anger right now is what we all, patients and caregivers alike, have gone through. Nobody wants to go through or see someone they love go through this. Get it out and then refocus on you mom's treatment. She is so fortunate to have you by her side, helping her in the battle of all battles. Try hard to keep yourself recharged, take time to make time...for yourself.
Again, I am sorry for what you are going through.
Ed