This may not be what you want to hear, but if your supervisor is unresponsive to your complaints then you may be best off switching jobs. Assuming it's even po

This may not be what you want to hear, but if your supervisor is unresponsive to your complaints then you may be best off switching jobs. Assuming it's even possible, changing your colleague's behavior would probably take a very long time. Being miserable at work drags you down emotionally and will affect your whole life, so I recommend getting out of there.