Welcome to the board Sweetface. What you are going through is a perfect example of how the Watchtower keeps people in their organization. A lot of people stay because they don't want to go through the situation you are in right now. As Gopher said to them the organization equals Jehovah so if you say something is wrong with the organization to them you are attacking God. They would see this as idolatry in any other religious group but are completely blind when it comes to the Watchtower. The Watchtower has pounded it in their heads that people don't leave for good reasons. They leave because they want to sleep around, do drugs or just leave "Jehovah's" council and do whatever they like. If you leave to become a Vegas stripper or leave to help the homeless it is all the same thing in their eyes. You have left the "truth" so you must be up to no good. They expect your life to fall apart and will be shocked when it doesn't.
Hopefully in time your sister will come to see some of the problems with the Watchtower and I'm sure you will be there for her if that happens. In the mean time I hope you will stick around this board. You will find lots of people here who are going through the same situation you are or have been through it.