Comment on the importance of loyalty and gratitude towards those who have helped you succeed in your career. Also, raise questions about the behavior of individuals who betray such people.
If some one helped you get where you are and you stab them in the back maybe you are the bully grow some thick skin you did not get where you have gotten with out the help of others. Firing is not your department it is HRs especially those that have helped you. maybe you are the bully?