Serial monitor error

Hi everyone. I just received my first Arduino Mega and I’m starting to experiment with it. I’m running a Windows 8.1 PC.
I’m running Flight Sim X along with BFF motion software on com5 at 9600 baud. My Arduino is also on com5. I’m trying to write a very simple program that will read the serial data from the BFF software send them to the serial monitor to confirm it’s working
right. The problem is when I try to start the serial monitor I get an error “Serial port ‘Com5’ is already in use. Try quitting any programs that may be using it”. Any suggestion on how to get around this thanks!

The Arduino is on one end of the serial port. ONE application can be on the other end. Should that be the Serial Monitor OR BFF? Yes is the wrong answer. So is both.