When you have to deal with difficult people, it helps to set up some ground rules.

Try a kindness reminder.
Mercy begins when we find it in our own heart for ourselves. It leads to feeling more tenderly toward people, and wanting to be done with the resentment and strife. If you're not feeling gentle and kind with yourself, you won't have it in you to give kindness to others.

Confront conflict with compassion.
Mercy doesn't mean you have to have lunch with this person, but you should come to understand that it's probably hard for them to be there at all. Even though they come across as arrogant or negative, that's a defense mechanism. A simple "hi" in passing is all you have to do.

Relinquish the idea of being "right".
People (including ourselves) can be sort of annoying. As you mature, you must ask yourself how much time you're going to devote to being right or correcting people's behaviors. When we withhold decency and good manners from someone, we're likely the ones who pay.

Self-acceptance takes time. These tips can help you handle situations with challenging people on your journey to self-actualization.