Hello,
I am not really faced this issue.
Apple's Bluetooth adapter is a USB device. USB devices can only be controlled by one OS at a time. You've probably told Fusion to automatically connect the Bluetooth adapter to the virtual machine, which will cause OS X to lose track of it.
The solution is to disconnect the Bluetooth adapter from the virtual machine (e.g. Virtual Machine > USB). If your mouse is Bluetooth, the easiest way to do this is to borrow a USB mouse.
Is this information helpful to you?