Sounds like you have a bunch of negative people in your family. Maybe you could use this move to Miami as a chance to change that. You can find someone else to take you to the hospital. It does not need to be your mom. It sounds like your mom is using your weight to keep you in your place....off balance and dependent. Maybe she thinks that if you are thin then lots of people would love you and you would not need her anymore. Maybe you should start keeping your own secrets. Just go through the process, meet new friends, have the surgery and when you start losing weight tell them you didn't let them know because of what happened last time you told them about your wls.
I believe we teach people how to treat us. Your family will only do what you allow them to do. If you don't stand for mistreatment, if you make an effort to stay away from negative people they will learn that they cannot be negative around you.
In order to be successful with wls we have to change the way we behave. Add getting rid of negative people to that list of lifestyle changes.