I'm not going to weigh in right now on your wife and her lack of concern for her child. My focus is on your daughter. My thoughts and prayers are w/you and your girls and I'm hoping and praying that you get in to see the surgeon as soon as possible and that there is something they can do to shrink the cyst so that she won't have to have surgery. Hopefully the surgeon can explain more about this cyst and will it return once it has shrunk or removed.
Definitely keep to your holiday plans for now. All of you need to have a good time and enjoy yourselves this weekend.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.