My mom used to say that resentment is like drinking poison in hopes of killing the other person.

People who upset you are giving you an opportunity to use your skills. When you get over how mean or offensive or annoying they are you can appreciate what they are helping you to learn about yourself.

I have a family member who is particularly difficult. When I joke about her (not to her face!) i call her my zen teacher. (Well, sometimes I call her less nice things than that. But apparently a lot of those words are censored on this forum...)