Well, most people haven't been sucessful in stopping an active fermentation once it's going. Usually, fermentation is allowed to finish, and then the wine is sweetened (after stabilizing) to taste.
Next time, you may want to start with a lower SG, allow it to finish, and then stabilize and sweeten. That would probably be more in line with what you're looking for.
If you really want to try to stop this fermentation, the first thing to do would to be get the wine very cold. Like 30 degrees. Hold it there for a month or so, then rack and stabilize with the campden and sorbate. It might work.