Can my supervisor retaliate against me for applying for another job within the company?

Hi, I recently applied for another job within the non-profit company that I work for. I notified my current supervisor of my interest in the new position and indicated on my work google calendar when I was interviewing for the position. It has come to my attention that my supervisor was discussing me taking on this new job with the human resources specialist, an intern, and one of my team members in the breakroom stating that she was "pissed" and would keep me at my current position until she found a replacement. The person who reported this to me via text message ask her if she could do this and my supervisor stated "trust me I will." I feel that she could try to do something to retaliate against me. Is it lawful for HR and supervisors to discuss personnel matters with interns & subordinates in out open in the office? I have been a model employee and just want to do the best job that I can. I will continue to work and act in a professional manner, but this bothers me. Is there anything that can be done as I feel that this is highly unethical and possibly illegal. Thanks for your time.